Working on multiple UI roots

Various refactorings and fixes to handle root-global and window-global state, root-specific palettes, and proper coordinate system changes (e.g., when opening menus).

UI events are posted and handled in the context of a specific root.

20 files changed, 269 insertions, 184 deletions

diff --git a/src/app.c b/src/app.c
index 39f399d1..85284d19 100644
--- a/src/app.c
+++ b/src/app.c
@@ -346,7 +346,7 @@ static void loadPrefs_App_(iApp *d) {
             }
 #endif
             else {
-                postCommandString_App(&cmdStr);
+                postCommandString_Root(NULL, &cmdStr);
             }
             deinit_String(&cmdStr);
         }
@@ -399,18 +399,25 @@ static iBool loadState_App_(iApp *d) {
             return iFalse;
         }
         setVersion_Stream(stream_File(f), version);
-        iDocumentWidget *doc = document_App(); /* first one is always from root 0 */
-        iDocumentWidget *current = NULL;
+        iDocumentWidget *doc = NULL; // document_App(); /* first one is always from root 0 */
+        iBool isFirstTab[2] = { iTrue, iTrue };
+        iDocumentWidget *current[2] = { NULL, NULL };
         while (!atEnd_File(f)) {
             readData_File(f, 4, magic);
             if (!memcmp(magic, magicTabDocument_App_, 4)) {
                 const int8_t flags = read8_File(f);
-                if (!doc) {
-                    setCurrent_Root(d->window->roots[flags & rootIndex1_DocumentStateFlag ? 1 : 0]);
+                const int rootIndex = flags & rootIndex1_DocumentStateFlag ? 1 : 0;
+                setCurrent_Root(d->window->roots[rootIndex]);
+                if (isFirstTab[rootIndex]) {
+                    isFirstTab[rootIndex] = iFalse;
+                    /* There is one pre-created tab in each root. */
+                    doc = document_Root(get_Root());
+                }
+                else {
                     doc = newTab_App(NULL, iFalse /* no switching */);
                 }
                 if (flags & current_DocumentStateFlag) {
-                    current = doc;
+                    current[rootIndex] = doc;
                 }
                 deserializeState_DocumentWidget(doc, stream_File(f));
                 doc = NULL;
@@ -421,7 +428,9 @@ static iBool loadState_App_(iApp *d) {
                 return iFalse;
             }
         }
-        postCommandf_App("tabs.switch page:%p", current);
+        iForIndices(i, current) {
+            postCommandf_Root(NULL, "tabs.switch page:%p", current[i]);
+        }
         setCurrent_Root(NULL);
         return iTrue;
     }
@@ -466,7 +475,7 @@ static uint32_t checkAsleep_App_(uint32_t interval, void *param) {
 
 static uint32_t postAutoReloadCommand_App_(uint32_t interval, void *param) {
     iUnused(param);
-    postCommand_App("document.autoreload");
+    postCommand_Root(NULL, "document.autoreload");
     return interval;
 }
 
@@ -660,7 +669,6 @@ static void init_App_(iApp *d, int argc, char **argv) {
     d->bookmarks = new_Bookmarks();
     d->tabEnum   = 0; /* generates unique IDs for tab pages */
     init_Periodic(&d->periodic);
-    setThemePalette_Color(d->prefs.theme);
 #if defined (iPlatformAppleDesktop)
     setupApplication_MacOS();
 #endif
@@ -691,11 +699,12 @@ static void init_App_(iApp *d, int argc, char **argv) {
     /* Widget state init. */
     processEvents_App(postedEventsOnly_AppEventMode);
     if (!loadState_App_(d)) {
-        postCommand_App("open url:about:help");
+        postCommand_Root(NULL, "open url:about:help");
     }
-    postCommand_App("window.unfreeze");
+    //setThemePalette_Color(d->prefs.theme);
+    postCommand_Root(NULL, "window.unfreeze");
     d->autoReloadTimer = SDL_AddTimer(60 * 1000, postAutoReloadCommand_App_, NULL);
-    postCommand_App("document.autoreload");
+    postCommand_Root(NULL, "document.autoreload");
 #if defined (LAGRANGE_ENABLE_IDLE_SLEEP)
     d->isIdling      = iFalse;
     d->lastEventTime = 0;
@@ -704,12 +713,12 @@ static void init_App_(iApp *d, int argc, char **argv) {
     d->isFinishedLaunching = iTrue;
     /* Run any commands that were pending completion of launch. */ {
         iForEach(StringList, i, d->launchCommands) {
-            postCommandString_App(i.value);
+            postCommandString_Root(NULL, i.value);
         }
     }
     /* URLs from the command line. */ {
         iConstForEach(StringList, i, openCmds) {
-            postCommandString_App(i.value);
+            postCommandString_Root(NULL, i.value);
         }
         iRelease(openCmds);
     }
@@ -824,7 +833,8 @@ const iString *debugInfo_App(void) {
     appendFormat_String(msg, "## Documents\n");
     iForEach(ObjectList, k, iClob(listDocuments_App(NULL))) {
         iDocumentWidget *doc = k.object;
-        appendFormat_String(msg, "### Tab %zu: %s\n",
+        appendFormat_String(msg, "### Tab %d.%zu: %s\n",
+                            constAs_Widget(doc)->root == get_Window()->roots[0] ? 0 : 1,
                             childIndex_Widget(constAs_Widget(doc)->parent, k.object),
                             cstr_String(bookmarkTitle_DocumentWidget(doc)));
         append_String(msg, collect_String(debugInfo_History(history_DocumentWidget(doc))));
@@ -918,7 +928,6 @@ void processEvents_App(enum iAppEventMode eventMode) {
     iApp *d = &app_;
     SDL_Event ev;
     iBool gotEvents = iFalse;
-    dispatchCommands_Periodic(&d->periodic);
     while (nextEvent_App_(d, eventMode, &ev)) {
 #if defined (iPlatformAppleMobile)
         if (processEvent_iOS(&ev)) {
@@ -930,7 +939,7 @@ void processEvents_App(enum iAppEventMode eventMode) {
                 d->isRunning = iFalse;
                 if (findWidget_App("prefs")) {
                     /* Make sure changed preferences get saved. */
-                    postCommand_App("prefs.dismiss");
+                    postCommand_Root(NULL, "prefs.dismiss");
                     processEvents_App(postedEventsOnly_AppEventMode);
                 }
                 goto backToMainLoop;
@@ -964,10 +973,10 @@ void processEvents_App(enum iAppEventMode eventMode) {
                     if (startsWithCase_CStr(ev.drop.file, "gemini:") ||
                         startsWithCase_CStr(ev.drop.file, "gopher:") ||
                         startsWithCase_CStr(ev.drop.file, "file:")) {
-                        postCommandf_App("~open newtab:%d url:%s", newTab, ev.drop.file);
+                        postCommandf_Root(NULL, "~open newtab:%d url:%s", newTab, ev.drop.file);
                     }
                     else {
-                        postCommandf_App(
+                        postCommandf_Root(NULL,
                             "~open newtab:%d url:%s", newTab, makeFileUrl_CStr(ev.drop.file));
                     }
                 }
@@ -1094,7 +1103,7 @@ static void runTickers_App_(iApp *d) {
     iConstForEach(Array, i, &pending->values) {
         const iTicker *ticker = i.value;
         if (ticker->callback) {
-            setCurrent_Root(findRoot_Window(d->window, ticker->context));
+            setCurrent_Root(findRoot_Window(d->window, ticker->context)); /* root might be NULL */
             ticker->callback(ticker->context);
         }
     }
@@ -1135,6 +1144,7 @@ static int run_App_(iApp *d) {
     SDL_AddEventWatch(resizeWatcher_, d); /* redraw window during resizing */
 #endif
     while (d->isRunning) {
+        dispatchCommands_Periodic(&d->periodic);
         processEvents_App(waitForNewEvents_AppEventMode);
         setCurrent_Root(NULL);
         runTickers_App_(d);
@@ -1242,8 +1252,7 @@ void postRefresh_App(void) {
     }
 }
 
-void postCommand_App(const char *command) {
-    iApp *d = &app_;
+void postCommand_Root(iRoot *d, const char *command) {
     iAssert(command);
     if (strlen(command) == 0) {
         return;
@@ -1255,8 +1264,8 @@ void postCommand_App(const char *command) {
     if (*command == '~') {
         /* Requires launch to be finished; defer it if needed. */
         command++;
-        if (!d->isFinishedLaunching) {
-            pushBackCStr_StringList(d->launchCommands, command);
+        if (!app_.isFinishedLaunching) {
+            pushBackCStr_StringList(app_.launchCommands, command);
             return;
         }
     }
@@ -1264,12 +1273,26 @@ void postCommand_App(const char *command) {
     ev.user.code = command_UserEventCode;
     /*ev.user.windowID = id_Window(get_Window());*/
     ev.user.data1 = strdup(command);
+    ev.user.data2 = d; /* all events are root-specific */
     SDL_PushEvent(&ev);
     if (app_.commandEcho) {
-        printf("[command] %s\n", command); fflush(stdout);
+        printf("[command] {%d} %s\n",
+               (d == NULL ? 0 : d == get_Window()->roots[0] ? 1 : 2),
+               command); fflush(stdout);
     }
 }
 
+void postCommandf_Root(iRoot *d, const char *command, ...) {
+    iBlock chars;
+    init_Block(&chars, 0);
+    va_list args;
+    va_start(args, command);
+    vprintf_Block(&chars, command, args);
+    va_end(args);
+    postCommand_Root(d, cstr_Block(&chars));
+    deinit_Block(&chars);
+}
+
 void postCommandf_App(const char *command, ...) {
     iBlock chars;
     init_Block(&chars, 0);
@@ -1277,16 +1300,23 @@ void postCommandf_App(const char *command, ...) {
     va_start(args, command);
     vprintf_Block(&chars, command, args);
     va_end(args);
-    postCommand_App(cstr_Block(&chars));
+    postCommand_Root(NULL, cstr_Block(&chars));
     deinit_Block(&chars);
 }
 
+void rootOrder_App(iRoot *roots[2]) {
+    const iWindow *win = app_.window;
+    roots[0] = get_Root();
+    roots[1] = (roots[0] == win->roots[0] ? win->roots[1] : win->roots[0]);
+}
+
 iAny *findWidget_App(const char *id) {
     if (!*id) return NULL;
-    iForIndices(i, app_.window->roots) {
-        iRoot *root = app_.window->roots[i];
-        if (root) {
-            iAny *found = findChild_Widget(root->widget, id);
+    iRoot *order[2];
+    rootOrder_App(order);
+    iForIndices(i, order) {
+        if (order[i]) {
+            iAny *found = findChild_Widget(order[i]->widget, id);
             if (found) {
                 return found;
             }
@@ -1485,7 +1515,7 @@ iDocumentWidget *document_Command(const char *cmd) {
 
 iDocumentWidget *newTab_App(const iDocumentWidget *duplicateOf, iBool switchToNew) {
     iApp *d = &app_;
-    iWidget *tabs = findWidget_App("doctabs");
+    iWidget *tabs = findWidget_Root("doctabs");
     setFlags_Widget(tabs, hidden_WidgetFlag, iFalse);
     iWidget *newTabButton = findChild_Widget(tabs, "newtab");
     removeChild_Widget(newTabButton->parent, newTabButton);
diff --git a/src/app.h b/src/app.h
index 0012d979..1b8360b3 100644
--- a/src/app.h
+++ b/src/app.h
@@ -107,14 +107,18 @@ iAny *      findWidget_App      (const char *id);
 void        addTicker_App       (iTickerFunc ticker, iAny *context);
 void        removeTicker_App    (iTickerFunc ticker, iAny *context);
 void        postRefresh_App     (void);
-void        postCommand_App     (const char *command);
+void        postCommand_Root    (iRoot *, const char *command);
+void        postCommandf_Root   (iRoot *, const char *command, ...);
 void        postCommandf_App    (const char *command, ...);
 
-iLocalDef void postCommandString_App(const iString *command) {
+iLocalDef void postCommandString_Root(iRoot *d, const iString *command) {
     if (command) {
-        postCommand_App(cstr_String(command));
+        postCommand_Root(d, cstr_String(command));
     }
 }
+iLocalDef void postCommand_App(const char *command) {
+    postCommandf_App(command);
+}
 
 iDocumentWidget *   document_Command    (const char *cmd);
 
diff --git a/src/history.c b/src/history.c
index 48820f6d..9f4e415b 100644
--- a/src/history.c
+++ b/src/history.c
@@ -21,6 +21,7 @@ ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
 SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE. */
 
 #include "history.h"
+#include "ui/root.h"
 #include "app.h"
 
 #include <the_Foundation/file.h>
@@ -244,9 +245,10 @@ iBool goBack_History(iHistory *d) {
     lock_Mutex(d->mtx);
     if (d->recentPos < size_Array(&d->recent) - 1) {
         d->recentPos++;
-        postCommandf_App("open history:1 scroll:%f url:%s",
-                         mostRecentUrl_History(d)->normScrollY,
-                         cstr_String(url_History(d, d->recentPos)));
+        postCommandf_Root(get_Root(),
+                          "open history:1 scroll:%f url:%s",
+                          mostRecentUrl_History(d)->normScrollY,
+                          cstr_String(url_History(d, d->recentPos)));
         unlock_Mutex(d->mtx);
         return iTrue;
     }
@@ -258,9 +260,10 @@ iBool goForward_History(iHistory *d) {
     lock_Mutex(d->mtx);
     if (d->recentPos > 0) {
         d->recentPos--;
-        postCommandf_App("open history:1 scroll:%f url:%s",
-                         mostRecentUrl_History(d)->normScrollY,
-                         cstr_String(url_History(d, d->recentPos)));
+        postCommandf_Root(get_Root(),
+                          "open history:1 scroll:%f url:%s",
+                          mostRecentUrl_History(d)->normScrollY,
+                          cstr_String(url_History(d, d->recentPos)));
         unlock_Mutex(d->mtx);
         return iTrue;
     }
diff --git a/src/periodic.c b/src/periodic.c
index eb4fb98d..0291ff98 100644
--- a/src/periodic.c
+++ b/src/periodic.c
@@ -70,10 +70,11 @@ iBool dispatchCommands_Periodic(iPeriodic *d) {
         const SDL_UserEvent ev = {
             .type  = SDL_USEREVENT,
             .code  = command_UserEventCode,
-            .data1 = (void *) cstr_String(&pc->command)
+            .data1 = (void *) cstr_String(&pc->command),
+            .data2 = findRoot_Window(get_Window(), pc->context)
         };
         iAssert(isInstance_Object(pc->context, &Class_Widget));
-        setCurrent_Root(findRoot_Window(get_Window(), pc->context));
+        setCurrent_Root(ev.data2);
         dispatchEvent_Widget(pc->context, (const SDL_Event *) &ev);
         wasPosted = iTrue;
     }
diff --git a/src/ui/color.c b/src/ui/color.c
index bcecb529..6cbbdf28 100644
--- a/src/ui/color.c
+++ b/src/ui/color.c
@@ -21,6 +21,7 @@ ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
 SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE. */
 
 #include "color.h"
+#include "root.h"
 #include "app.h"
 
 #include <the_Foundation/string.h>
@@ -65,7 +66,11 @@ static const iColor lightPalette_[] = {
     { 0,   150, 0,   255 },
 };
 
-static iColor palette_[max_ColorId];
+static iColor uiPalette_[tmFirst_ColorId]; /* not theme-specific */
+
+iColor *paletteColor_(enum iColorId id) {
+    return id < tmFirst_ColorId ? &uiPalette_[id] : &get_Root()->tmPalette[id - tmFirst_ColorId];
+}
 
 iLocalDef void copy_(enum iColorId dst, enum iColorId src) {
     set_Color(dst, get_Color(src));
@@ -73,7 +78,7 @@ iLocalDef void copy_(enum iColorId dst, enum iColorId src) {
 
 void setThemePalette_Color(enum iColorTheme theme) {
     const iPrefs *prefs = prefs_App();
-    memcpy(palette_, isDark_ColorTheme(theme) ? darkPalette_ : lightPalette_, sizeof(darkPalette_));
+    memcpy(uiPalette_, isDark_ColorTheme(theme) ? darkPalette_ : lightPalette_, sizeof(darkPalette_));
     const int accentHi    = (prefs->accent == cyan_ColorAccent ? cyan_ColorId : orange_ColorId);
     const int accentLo    = (prefs->accent == cyan_ColorAccent ? teal_ColorId : brown_ColorId);
     const int altAccentHi = (prefs->accent == cyan_ColorAccent ? orange_ColorId : cyan_ColorId);
@@ -298,8 +303,8 @@ void setThemePalette_Color(enum iColorTheme theme) {
     set_Color(uiTextShortcut_ColorId, mix_Color(get_Color(uiTextShortcut_ColorId),
                                                 get_Color(uiBackground_ColorId),
                                                 0.4f));
-    palette_[uiMarked_ColorId].a = 128;
-    palette_[uiMatching_ColorId].a = 128;
+    uiPalette_[uiMarked_ColorId  ].a = 128;
+    uiPalette_[uiMatching_ColorId].a = 128;
     if (deviceType_App() == phone_AppDeviceType) {
         copy_(uiInputBackground_ColorId, uiBackgroundSidebar_ColorId);
         copy_(uiInputFrame_ColorId, uiBackgroundSidebar_ColorId);
@@ -311,14 +316,14 @@ void setThemePalette_Color(enum iColorTheme theme) {
 iColor get_Color(int color) {
     const iColor *rgba = &transparent_;
     if (color >= 0 && color < max_ColorId) {
-        rgba = &palette_[color];
+        rgba = paletteColor_(color);
     }
     return *rgba;
 }
 
 void set_Color(int color, iColor rgba) {
     if (color >= uiBackground_ColorId && color < max_ColorId) {
-        palette_[color] = rgba;
+        *paletteColor_(color) = rgba;
     }
 }
 
@@ -341,7 +346,7 @@ iLocalDef iBool equal_Color_(const iColor *x, const iColor *y) {
 int darker_Color(int color) {
     const iColor rgb = get_Color(color);
     for (int i = 0; i < uiFirst_ColorId; i++) {
-        if (equal_Color_(&rgb, &palette_[i])) {
+        if (equal_Color_(&rgb, paletteColor_(i))) {
             return i > 0 ? i - 1 : i;
         }
     }
@@ -351,7 +356,7 @@ int darker_Color(int color) {
 int lighter_Color(int color) {
     const iColor rgb = get_Color(color);
     for (int i = 0; i < uiFirst_ColorId; i++) {
-        if (equal_Color_(&rgb, &palette_[i])) {
+        if (equal_Color_(&rgb, paletteColor_(i))) {
             return i < uiFirst_ColorId - 1 ? i + 1 : i;
         }
     }
diff --git a/src/ui/color.h b/src/ui/color.h
index cd2f95d3..c0db4382 100644
--- a/src/ui/color.h
+++ b/src/ui/color.h
@@ -115,9 +115,7 @@ enum iColorId {
     uiTextAppTitle_ColorId,
     uiBackgroundSidebar_ColorId,
     uiBackgroundMenu_ColorId,
-    tmLinkCustomIconVisited_ColorId, /* derived from other theme colors */
-    tmAltTextBackground_ColorId,     /* derived from other theme colors */
-
+    
     /* content theme colors */
     tmFirst_ColorId,
     tmBackground_ColorId = tmFirst_ColorId,
@@ -133,9 +131,9 @@ enum iColorId {
     tmBannerTitle_ColorId,
     tmBannerIcon_ColorId,
     tmBannerSideTitle_ColorId,
-    tmOutlineHeadingAbove_ColorId,
-    tmOutlineHeadingBelow_ColorId,
     tmInlineContentMetadata_ColorId,
+    tmAltTextBackground_ColorId,     /* derived from other theme colors */
+    tmLinkCustomIconVisited_ColorId, /* derived from other theme colors */
     tmBadLink_ColorId,
 
     tmLinkIcon_ColorId,
@@ -159,7 +157,8 @@ enum iColorId {
     tmGopherLinkDomain_ColorId,
     tmGopherLinkLastVisitDate_ColorId,
 
-    max_ColorId
+    max_ColorId,
+    tmMax_ColorId = max_ColorId - tmFirst_ColorId
 };
 
 iLocalDef iBool isLink_ColorId(enum iColorId d) {
diff --git a/src/ui/documentwidget.c b/src/ui/documentwidget.c
index 79678f56..2f20958f 100644
--- a/src/ui/documentwidget.c
+++ b/src/ui/documentwidget.c
@@ -1234,7 +1234,10 @@ static void fetch_DocumentWidget_(iDocumentWidget *d) {
         iRelease(d->request);
         d->request = NULL;
     }
-    postCommandf_App("document.request.started doc:%p url:%s", d, cstr_String(d->mod.url));
+    postCommandf_Root(as_Widget(d)->root,
+                      "document.request.started doc:%p url:%s",
+                      d,
+                      cstr_String(d->mod.url));
     clear_ObjectList(d->media);
     d->certFlags = 0;
     setLinkNumberMode_DocumentWidget_(d, iFalse);
@@ -1318,7 +1321,7 @@ static iBool updateFromHistory_DocumentWidget_(iDocumentWidget *d) {
         updateVisible_DocumentWidget_(d);
         moveSpan_SmoothScroll(&d->scrollY, 0, 0); /* clamp position to new max */
         cacheDocumentGlyphs_DocumentWidget_(d);
-        postCommandf_App("document.changed doc:%p url:%s", d, cstr_String(d->mod.url));
+        postCommandf_Root(as_Widget(d)->root, "document.changed doc:%p url:%s", d, cstr_String(d->mod.url));
         return iTrue;
     }
     else if (!isEmpty_String(d->mod.url)) {
@@ -1391,7 +1394,7 @@ static void scrollToHeading_DocumentWidget_(iDocumentWidget *d, const char *head
     iConstForEach(Array, h, headings_GmDocument(d->doc)) {
         const iGmHeading *head = h.value;
         if (startsWithCase_Rangecc(head->text, heading)) {
-            postCommandf_App("document.goto loc:%p", head->text.start);
+            postCommandf_Root(as_Widget(d)->root, "document.goto loc:%p", head->text.start);
             break;
         }
     }
@@ -1514,7 +1517,7 @@ static void checkResponse_DocumentWidget_(iDocumentWidget *d) {
                                                cstr_Rangecc(urlScheme_String(d->mod.url)))) {
                         /* Redirects with the same scheme are automatic. */
                         visitUrl_Visited(visited_App(), d->mod.url, transient_VisitedUrlFlag);
-                        postCommandf_App(
+                        postCommandf_Root(as_Widget(d)->root,
                             "open doc:%p redirect:%d url:%s", d, d->redirectCount + 1, cstr_String(dstUrl));
                     }
                     else {
@@ -2037,7 +2040,7 @@ static iBool handleCommand_DocumentWidget_(iDocumentWidget *d, const char *cmd)
         if (!isEmpty_Block(d->certFingerprint) && !isEmpty_Range(&host)) {
             setTrusted_GmCerts(certs_App(), host, d->certFingerprint, &d->certExpiry);
             d->certFlags |= trusted_GmCertFlag;
-            postCommand_App("document.info");
+            postCommand_Widget(w, "document.info");
             updateTrust_DocumentWidget_(d, NULL);
             redoLayout_GmDocument(d->doc);
             invalidate_DocumentWidget_(d);
@@ -2065,7 +2068,7 @@ static iBool handleCommand_DocumentWidget_(iDocumentWidget *d, const char *cmd)
         SDL_SetClipboardText(cstr_String(copied));
         delete_String(copied);
         if (flags_Widget(w) & touchDrag_WidgetFlag) {
-            postCommand_App("document.select arg:0");
+            postCommand_Widget(w, "document.select arg:0");
         }
         return iTrue;
     }
@@ -2102,13 +2105,13 @@ static iBool handleCommand_DocumentWidget_(iDocumentWidget *d, const char *cmd)
         }
         appendCStr_String(url, "?");
         append_String(url, value);
-        postCommandf_App("open url:%s", cstr_String(url));
+        postCommandf_Root(w->root, "open url:%s", cstr_String(url));
         delete_String(value);
         return iTrue;
     }
     else if (equal_Command(cmd, "valueinput.cancelled") &&
              equal_Rangecc(range_Command(cmd, "id"), "document.input.submit") && document_App() == d) {
-        postCommand_App("navigate.back");
+        postCommand_Root(get_Root(), "navigate.back");
         return iTrue;
     }
     else if (equalWidget_Command(cmd, w, "document.request.updated") &&
@@ -2149,7 +2152,7 @@ static iBool handleCommand_DocumentWidget_(iDocumentWidget *d, const char *cmd)
         iReleasePtr(&d->request);
         updateVisible_DocumentWidget_(d);
         d->drawBufs->flags |= updateSideBuf_DrawBufsFlag;
-        postCommandf_App("document.changed doc:%p url:%s", d, cstr_String(d->mod.url));
+        postCommandf_Root(w->root, "document.changed doc:%p url:%s", d, cstr_String(d->mod.url));
         /* Check for a pending goto. */
         if (!isEmpty_String(&d->pendingGotoHeading)) {
             scrollToHeading_DocumentWidget_(d, cstr_String(&d->pendingGotoHeading));
@@ -2193,12 +2196,12 @@ static iBool handleCommand_DocumentWidget_(iDocumentWidget *d, const char *cmd)
     }
     else if (equal_Command(cmd, "document.stop") && document_App() == d) {
         if (d->request) {
-            postCommandf_App(
+            postCommandf_Root(w->root,
                 "document.request.cancelled doc:%p url:%s", d, cstr_String(d->mod.url));
             iReleasePtr(&d->request);
             if (d->state != ready_RequestState) {
                 d->state = ready_RequestState;
-                postCommand_App("navigate.back");
+                postCommand_Root(w->root, "navigate.back");
             }
             updateFetchProgress_DocumentWidget_(d);
             return iTrue;
@@ -2267,7 +2270,7 @@ static iBool handleCommand_DocumentWidget_(iDocumentWidget *d, const char *cmd)
     }
     else if (equal_Command(cmd, "navigate.back") && document_App() == d) {
         if (d->request) {
-            postCommandf_App(
+            postCommandf_Root(w->root,
                 "document.request.cancelled doc:%p url:%s", d, cstr_String(d->mod.url));
             iReleasePtr(&d->request);
             updateFetchProgress_DocumentWidget_(d);
@@ -2291,14 +2294,14 @@ static iBool handleCommand_DocumentWidget_(iDocumentWidget *d, const char *cmd)
                 if (parts.path.end[-1] == '/') break;
                 parts.path.end--;
             }
-            postCommandf_App(
+            postCommandf_Root(w->root,
                 "open url:%s",
                 cstr_Rangecc((iRangecc){ constBegin_String(d->mod.url), parts.path.end }));
         }
         return iTrue;
     }
     else if (equal_Command(cmd, "navigate.root") && document_App() == d) {
-        postCommandf_App("open url:%s/", cstr_Rangecc(urlRoot_String(d->mod.url)));
+        postCommandf_Root(w->root, "open url:%s/", cstr_Rangecc(urlRoot_String(d->mod.url)));
         return iTrue;
     }
     else if (equalWidget_Command(cmd, w, "scroll.moved")) {
@@ -2390,7 +2393,7 @@ static iBool handleCommand_DocumentWidget_(iDocumentWidget *d, const char *cmd)
             }
         }
         if (flags_Widget(w) & touchDrag_WidgetFlag) {
-            postCommand_App("document.select arg:0"); /* we can't handle both at the same time */
+            postCommand_Root(w->root, "document.select arg:0"); /* we can't handle both at the same time */
         }
         invalidateWideRunsWithNonzeroOffset_DocumentWidget_(d); /* markers don't support offsets */
         resetWideRuns_DocumentWidget_(d);
@@ -2593,8 +2596,7 @@ static iBool processMediaEvents_DocumentWidget_(iDocumentWidget *d, const SDL_Ev
                         { cstrCollect_String(metadataLabel_Player(plr)), 0, 0, NULL },
                     },
                     1);
-                openMenu_Widget(d->playerMenu,
-                                localCoord_Widget(constAs_Widget(d), bottomLeft_Rect(ui.menuRect)));
+                openMenu_Widget(d->playerMenu, bottomLeft_Rect(ui.menuRect));
                 return iTrue;
             }
         }
@@ -2699,7 +2701,8 @@ static iBool processEvent_DocumentWidget_(iDocumentWidget *d, const SDL_Event *e
                         d->hoverLink = run;
                     }
                     else {
-                        postCommandf_App("open newtab:%d url:%s",
+                        postCommandf_Root(w->root,
+                                          "open newtab:%d url:%s",
                                          d->ordinalMode ==
                                                  numbersAndAlphabet_DocumentLinkOrdinalMode
                                              ? openTabMode_Sym(modState_Keys())
@@ -2813,15 +2816,15 @@ static iBool processEvent_DocumentWidget_(iDocumentWidget *d, const SDL_Event *e
     }
     if (ev->type == SDL_MOUSEBUTTONDOWN) {
         if (ev->button.button == SDL_BUTTON_X1) {
-            postCommand_App("navigate.back");
+            postCommand_Root(w->root, "navigate.back");
             return iTrue;
         }
         if (ev->button.button == SDL_BUTTON_X2) {
-            postCommand_App("navigate.forward");
+            postCommand_Root(w->root, "navigate.forward");
             return iTrue;
         }
         if (ev->button.button == SDL_BUTTON_MIDDLE && d->hoverLink) {
-            postCommandf_App("open newtab:%d url:%s",
+            postCommandf_Root(w->root, "open newtab:%d url:%s",
                              modState_Keys() & KMOD_SHIFT ? 1 : 2,
                              cstr_String(linkUrl_GmDocument(d->doc, d->hoverLink->linkId)));
             return iTrue;
@@ -2967,7 +2970,7 @@ static iBool processEvent_DocumentWidget_(iDocumentWidget *d, const SDL_Event *e
                         },
                         3);
 #endif
-                    postCommand_App("document.select arg:1");
+                    postCommand_Root(w->root, "document.select arg:1");
                     return iTrue;
                 }
                 d->menu = makeMenu_Widget(w, data_Array(&items), size_Array(&items));
@@ -3188,7 +3191,7 @@ static iBool processEvent_DocumentWidget_(iDocumentWidget *d, const SDL_Event *e
                         refresh_Widget(w);
                     }
                     else if (linkFlags & supportedProtocol_GmLinkFlag) {
-                        postCommandf_App("open newtab:%d url:%s",
+                        postCommandf_Root(w->root, "open newtab:%d url:%s",
                                          openTabMode_Sym(modState_Keys()),
                                          cstr_String(absoluteUrl_String(
                                              d->mod.url, linkUrl_GmDocument(d->doc, linkId))));
@@ -3221,7 +3224,7 @@ static iBool processEvent_DocumentWidget_(iDocumentWidget *d, const SDL_Event *e
                     if (bannerType_DocumentWidget_(d) == certificateWarning_GmDocumentBanner &&
                         pos_Click(&d->click).y - top_Rect(banRect) >
                             lineHeight_Text(banner_FontId) * 2) {
-                        postCommand_App("document.info");
+                        postCommand_Widget(d, "document.info");
                     }
                     else {
                         postCommand_Widget(d, "navigate.root");
diff --git a/src/ui/inputwidget.c b/src/ui/inputwidget.c
index 9d360f47..a40b77eb 100644
--- a/src/ui/inputwidget.c
+++ b/src/ui/inputwidget.c
@@ -754,10 +754,10 @@ static iBool processEvent_InputWidget_(iInputWidget *d, const SDL_Event *ev) {
         return iTrue;
     }
     if (ev->type == SDL_MOUSEMOTION && isHover_Widget(d)) {
-        const iInt2 local = localCoord_Widget(w, init_I2(ev->motion.x, ev->motion.y));
+        const iInt2 inner = windowToInner_Widget(w, init_I2(ev->motion.x, ev->motion.y));
         setCursor_Window(get_Window(),
-                         local.x >= 2 * gap_UI + d->leftPadding &&
-                                 local.x < width_Widget(w) - d->rightPadding
+                         inner.x >= 2 * gap_UI + d->leftPadding &&
+                         inner.x < width_Widget(w) - d->rightPadding
                              ? SDL_SYSTEM_CURSOR_IBEAM
                              : SDL_SYSTEM_CURSOR_ARROW);
     }
diff --git a/src/ui/keys.c b/src/ui/keys.c
index 456ca928..6ad9d360 100644
--- a/src/ui/keys.c
+++ b/src/ui/keys.c
@@ -438,7 +438,7 @@ iBool processEvent_Keys(const SDL_Event *ev) {
                 postCommandf_App("%s repeat:1", cstr_String(&bind->command));
             }
             else {
-                postCommandString_App(&bind->command);
+                postCommandString_Root(NULL, &bind->command);
             }
             return iTrue;
         }
diff --git a/src/ui/lookupwidget.c b/src/ui/lookupwidget.c
index d8e594de..e0de97bf 100644
--- a/src/ui/lookupwidget.c
+++ b/src/ui/lookupwidget.c
@@ -654,11 +654,14 @@ static iBool processEvent_LookupWidget_(iLookupWidget *d, const SDL_Event *ev) {
              (equal_Command(cmd, "layout.changed") &&
               equal_Rangecc(range_Command(cmd, "id"), "navbar"))) {
         /* Position the lookup popup under the URL bar. */ {
-            const iInt2 rootSize = size_Root(w->root);
-            const iRect navBarBounds = bounds_Widget(findWidget_App("navbar"));
-            setFixedSize_Widget(w, init_I2(width_Widget(findWidget_App("url")),
+            iRoot *root = w->root;
+            const iInt2 rootSize = size_Root(root);
+            const iRect navBarBounds = bounds_Widget(findChild_Widget(root->widget, "navbar"));
+            printf("navbar x:%d w:%d\n", navBarBounds.pos.x, navBarBounds.size.x);
+            iWidget *url = findChild_Widget(root->widget, "url");
+            setFixedSize_Widget(w, init_I2(width_Widget(url),
                                            (rootSize.y - bottom_Rect(navBarBounds)) / 2));
-            setPos_Widget(w, bottomLeft_Rect(bounds_Widget(findWidget_App("url"))));
+            setPos_Widget(w, windowToLocal_Widget(w, bottomLeft_Rect(bounds_Widget(url))));
 #if defined (iPlatformAppleMobile)
             /* Adjust height based on keyboard size. */ {
                 w->rect.size.y = visibleRootSize_Window(window).y - top_Rect(bounds_Widget(w));
@@ -667,6 +670,7 @@ static iBool processEvent_LookupWidget_(iLookupWidget *d, const SDL_Event *ev) {
                     safeAreaInsets_iOS(&l, NULL, &r, NULL);
                     w->rect.size.x = rootSize.x - l - r;
                     w->rect.pos.x  = l;
+                    /* TODO: Need to use windowToLocal_Widget? */
                 }
             }
 #endif
@@ -694,7 +698,7 @@ static iBool processEvent_LookupWidget_(iLookupWidget *d, const SDL_Event *ev) {
             setText_InputWidget(url, url_DocumentWidget(document_App()));
             showCollapsed_Widget(w, iFalse);
             setCursor_LookupWidget_(d, iInvalidPos);
-            postCommandString_App(&item->command);
+            postCommandString_Root(get_Root(), &item->command);
             postCommand_App("focus.set id:"); /* unfocus */
         }
         return iTrue;
diff --git a/src/ui/root.c b/src/ui/root.c
index f91c3ba5..8faeb215 100644
--- a/src/ui/root.c
+++ b/src/ui/root.c
@@ -255,6 +255,13 @@ iRoot *get_Root(void) {
     return activeRoot_;
 }
 
+iAnyObject *findWidget_Root(const char *id) {
+    if (activeRoot_) {
+        return findChild_Widget(activeRoot_->widget, id);
+    }
+    return NULL;
+}
+
 void destroyPending_Root(iRoot *d) {
     setCurrent_Root(d);    
     iForEach(PtrSet, i, d->pendingDestruction) {
@@ -286,7 +293,7 @@ static iBool handleRootCommands_(iWidget *root, const char *cmd) {
         iWidget *menu = findChild_Widget(button, "menu");
         iAssert(menu);
         if (!isVisible_Widget(menu)) {
-            openMenu_Widget(menu, init_I2(0, button->rect.size.y));
+            openMenu_Widget(menu, bottomLeft_Rect(bounds_Widget(button)));
         }
         else {
             closeMenu_Widget(menu);
@@ -619,10 +626,10 @@ static iBool handleNavBarCommands_(iWidget *navBar, const char *cmd) {
             iString *newUrl = copy_String(text_InputWidget(url));
             trim_String(newUrl);
             if (willPerformSearchQuery_(newUrl)) {
-                postCommandf_App("open url:%s", cstr_String(searchQueryUrl_App(newUrl)));
+                postCommandf_Root(navBar->root, "open url:%s", cstr_String(searchQueryUrl_App(newUrl)));
             }
             else {
-                postCommandf_App(
+                postCommandf_Root(navBar->root,
                     "open url:%s",
                     cstr_String(absoluteUrl_String(&iStringLiteral(""), collect_String(newUrl))));
             }
@@ -677,6 +684,7 @@ static iBool handleNavBarCommands_(iWidget *navBar, const char *cmd) {
     else if (equal_Command(cmd, "mouse.clicked") && arg_Command(cmd)) {
         iWidget *widget = pointer_Command(cmd);
         iWidget *menu = findWidget_App("doctabs.menu");
+        iAssert(menu->root == navBar->root);
         if (isTabButton_Widget(widget)) {
             if (!isVisible_Widget(menu)) {
                 iWidget *tabs = findWidget_App("doctabs");
@@ -758,7 +766,7 @@ static iBool handleToolBarCommands_(iWidget *toolBar, const char *cmd) {
         argLabel_Command(cmd, "button") == SDL_BUTTON_RIGHT) {
         iWidget *menu = findChild_Widget(toolBar, "toolbar.menu");
         arrange_Widget(menu);
-        openMenu_Widget(menu, init_I2(0, -height_Widget(menu)));
+        openMenu_Widget(menu, innerToWindow_Widget(menu, init_I2(0, -height_Widget(menu))));
         return iTrue;
     }
     else if (equal_Command(cmd, "toolbar.showview")) {
@@ -868,6 +876,7 @@ void updateMetrics_Root(iRoot *d) {
 
 void createUserInterface_Root(iRoot *d) {
     iWidget *root = d->widget = new_Widget();
+    iAssert(root->root == d);
     setId_Widget(root, "root");
     /* Children of root cover the entire window. */
     setFlags_Widget(
diff --git a/src/ui/root.h b/src/ui/root.h
index 39e7bf3c..e5fdcbe4 100644
--- a/src/ui/root.h
+++ b/src/ui/root.h
@@ -1,6 +1,7 @@
 #pragma once
 
 #include "widget.h"
+#include "color.h"
 #include <the_Foundation/ptrset.h>
 #include <the_Foundation/vec2.h>
 
@@ -8,12 +9,10 @@ iDeclareType(Root)
     
 struct Impl_Root {
     iWidget *  widget;
-    iWidget *  hover;
-    iWidget *  mouseGrab;
-    iWidget *  focus;
     iPtrArray *onTop; /* order is important; last one is topmost */
     iPtrSet *  pendingDestruction;
     int        loadAnimTimer;
+    iColor     tmPalette[tmMax_ColorId]; /* theme-specific palette */
 };
 
 iDeclareTypeConstruction(Root)
@@ -24,6 +23,7 @@ void        createUserInterface_Root            (iRoot *);
 
 void        setCurrent_Root                     (iRoot *);
 iRoot *     get_Root                            (void);
+iAnyObject *findWidget_Root                     (const char *id); /* under current Root */
 
 iPtrArray * onTop_Root                          (iRoot *);
 void        destroyPending_Root                 (iRoot *);
diff --git a/src/ui/sidebarwidget.c b/src/ui/sidebarwidget.c
index 62d195fb..7d08b83a 100644
--- a/src/ui/sidebarwidget.c
+++ b/src/ui/sidebarwidget.c
@@ -713,14 +713,14 @@ static void itemClicked_SidebarWidget_(iSidebarWidget *d, const iSidebarItem *it
             break;
         }
         case feeds_SidebarMode: {
-            postCommandString_App(
+            postCommandString_Root(get_Root(),
                 feedEntryOpenCommand_String(&item->url, openTabMode_Sym(modState_Keys())));
             break;
         }
         case bookmarks_SidebarMode:
         case history_SidebarMode: {
             if (!isEmpty_String(&item->url)) {
-                postCommandf_App("open newtab:%d url:%s",
+                postCommandf_Root(get_Root(), "open newtab:%d url:%s",
                                  openTabMode_Sym(modState_Keys()),
                                  cstr_String(&item->url));
             }
@@ -961,13 +961,13 @@ static iBool processEvent_SidebarWidget_(iSidebarWidget *d, const SDL_Event *ev)
         }
         else if (isCommand_Widget(w, ev, "mouse.moved")) {
             if (isResizing_SidebarWidget_(d)) {
-                const iInt2 local = localCoord_Widget(w, coord_Command(cmd));
+                const iInt2 inner = windowToInner_Widget(w, coord_Command(cmd));
                 const int resMid = d->resizer->rect.size.x / 2;
                 setWidth_SidebarWidget(
                     d,
                     ((d->side == left_SideBarSide
-                         ? local.x
-                          : (size_Root(w->root).x - coord_Command(cmd).x)) +
+                         ? inner.x
+                          : (right_Rect(rect_Root(w->root)) - coord_Command(cmd).x)) +
                      resMid) / (float) gap_UI);
             }
             return iTrue;
@@ -1086,7 +1086,7 @@ static iBool processEvent_SidebarWidget_(iSidebarWidget *d, const SDL_Event *ev)
             const iSidebarItem *item = d->contextItem;
             if (item) {
                 if (isCommand_Widget(w, ev, "feed.entry.opentab")) {
-                    postCommandString_App(feedEntryOpenCommand_String(&item->url, 1));
+                    postCommandString_Root(get_Root(), feedEntryOpenCommand_String(&item->url, 1));
                     return iTrue;
                 }
                 if (isCommand_Widget(w, ev, "feed.entry.toggleread")) {
diff --git a/src/ui/touch.c b/src/ui/touch.c
index e49fce2a..b2c52526 100644
--- a/src/ui/touch.c
+++ b/src/ui/touch.c
@@ -233,7 +233,8 @@ static void dispatchNotification_Touch_(const iTouch *d, int code) {
             .type = SDL_USEREVENT,
             .timestamp = SDL_GetTicks(),
             .code = code,
-            .data1 = d->affinity
+            .data1 = d->affinity,
+            .data2 = d->affinity->root
         });
         setCurrent_Root(oldRoot);
     }
diff --git a/src/ui/util.c b/src/ui/util.c
index edfd43cc..b487e13d 100644
--- a/src/ui/util.c
+++ b/src/ui/util.c
@@ -733,12 +733,13 @@ iWidget *makeMenu_Widget(iWidget *parent, const iMenuItem *items, size_t n) {
     return menu;
 }
 
-void openMenu_Widget(iWidget *d, iInt2 coord) {
-    openMenuFlags_Widget(d, coord, iTrue);
+void openMenu_Widget(iWidget *d, iInt2 windowCoord) {
+    openMenuFlags_Widget(d, windowCoord, iTrue);
 }
 
-void openMenuFlags_Widget(iWidget *d, iInt2 coord, iBool postCommands) {
-    const iInt2 rootSize        = size_Window(get_Window());
+void openMenuFlags_Widget(iWidget *d, iInt2 windowCoord, iBool postCommands) {
+    const iRect rootRect        = rect_Root(d->root);
+    const iInt2 rootSize        = rootRect.size;
     const iBool isPortraitPhone = (deviceType_App() == phone_AppDeviceType && isPortrait_App());
     const iBool isSlidePanel    = (flags_Widget(d) & horizontalOffset_WidgetFlag) != 0;
     if (postCommands) {
@@ -756,7 +757,7 @@ void openMenuFlags_Widget(iWidget *d, iInt2 coord, iBool postCommands) {
         if (!isSlidePanel) {
             setFlags_Widget(d, borderTop_WidgetFlag, iTrue);
         }
-        d->rect.size.x = size_Window(get_Window()).x;
+        d->rect.size.x = rootSize.x;
     }
     /* Update item fonts. */ {
         iForEach(ObjectList, i, children_Widget(d)) {
@@ -790,14 +791,14 @@ void openMenuFlags_Widget(iWidget *d, iInt2 coord, iBool postCommands) {
         }
     }
     else {
-        d->rect.pos = coord;
+        d->rect.pos = windowToLocal_Widget(d, windowCoord);
     }
     /* Ensure the full menu is visible. */
     const iRect bounds       = bounds_Widget(d);
-    int         leftExcess   = -left_Rect(bounds);
-    int         rightExcess  = right_Rect(bounds) - rootSize.x;
-    int         topExcess    = -top_Rect(bounds);
-    int         bottomExcess = bottom_Rect(bounds) - rootSize.y;
+    int         leftExcess   = left_Rect(rootRect) - left_Rect(bounds);
+    int         rightExcess  = right_Rect(bounds) - right_Rect(rootRect);
+    int         topExcess    = top_Rect(rootRect) - top_Rect(bounds);
+    int         bottomExcess = bottom_Rect(bounds) - bottom_Rect(rootRect);
 #if defined (iPlatformAppleMobile)
     /* Reserve space for the system status bar. */ {
         float l, t, r, b;
@@ -868,7 +869,7 @@ int checkContextMenu_Widget(iWidget *menu, const SDL_Event *ev) {
         }
         const iInt2 mousePos = init_I2(ev->button.x, ev->button.y);
         if (contains_Widget(menu->parent, mousePos)) {
-            openMenu_Widget(menu, localCoord_Widget(menu->parent, mousePos));
+            openMenu_Widget(menu, mousePos);
             return 0x2;
         }
     }
@@ -1044,7 +1045,7 @@ void showTabPage_Widget(iWidget *tabs, const iWidget *page) {
     }
     /* Notify. */
     if (!isEmpty_String(id_Widget(page))) {
-        postCommandf_App("tabs.changed id:%s", cstr_String(id_Widget(page)));
+        postCommandf_Root(page->root, "tabs.changed id:%s", cstr_String(id_Widget(page)));
     }
 }
 
@@ -1160,7 +1161,7 @@ static iBool slidePanelHandler_(iWidget *d, const char *cmd) {
     if (equal_Command(cmd, "panel.open")) {
         iWidget *button = pointer_Command(cmd);
         iWidget *panel = userData_Object(button);
-        openMenu_Widget(panel, zero_I2());
+        openMenu_Widget(panel, innerToWindow_Widget(panel, zero_I2()));
         setFlags_Widget(panel, disabled_WidgetFlag, iFalse);
 //        updateTextCStr_LabelWidget(findWidget_App("panel.back"), );
         return iTrue;
diff --git a/src/ui/util.h b/src/ui/util.h
index aaffb1b8..b8d10cf0 100644
--- a/src/ui/util.h
+++ b/src/ui/util.h
@@ -212,8 +212,8 @@ struct Impl_MenuItem {
 };
 
 iWidget *   makeMenu_Widget     (iWidget *parent, const iMenuItem *items, size_t n); /* returns no ref */
-void        openMenu_Widget     (iWidget *, iInt2 coord);
-void        openMenuFlags_Widget(iWidget *d, iInt2 coord, iBool postCommands);
+void        openMenu_Widget     (iWidget *, iInt2 windowCoord);
+void        openMenuFlags_Widget(iWidget *, iInt2 windowCoord, iBool postCommands);
 void        closeMenu_Widget    (iWidget *);
 
 iLabelWidget *  findMenuItem_Widget (iWidget *menu, const char *command);
diff --git a/src/ui/widget.c b/src/ui/widget.c
index 5d924b57..6d6bc202 100644
--- a/src/ui/widget.c
+++ b/src/ui/widget.c
@@ -99,7 +99,7 @@ static void aboutToBeDestroyed_Widget_(iWidget *d) {
         removeOne_PtrArray(onTop_Root(d->root), d);
     }
     if (isHover_Widget(d)) {
-        d->root->hover = NULL;
+        get_Window()->hover = NULL;
     }
     iForEach(ObjectList, i, d->children) {
         aboutToBeDestroyed_Widget_(as_Widget(i.object));
@@ -675,16 +675,30 @@ static void applyVisualOffset_Widget_(const iWidget *d, iInt2 *pos) {
 
 iRect bounds_Widget(const iWidget *d) {
     iRect bounds = d->rect;
-    applyVisualOffset_Widget_(d, &bounds.pos);
+    bounds.pos = localToWindow_Widget(d, bounds.pos);
+    return bounds;
+}
+
+iInt2 localToWindow_Widget(const iWidget *d, iInt2 localCoord) {
+    iInt2 window = localCoord;
+    applyVisualOffset_Widget_(d, &window);
     for (const iWidget *w = d->parent; w; w = w->parent) {
         iInt2 pos = w->rect.pos;
         applyVisualOffset_Widget_(w, &pos);
-        addv_I2(&bounds.pos, pos);
+        addv_I2(&window, pos);
     }
 #if defined (iPlatformMobile)
-    bounds.pos.y += value_Anim(&get_Window()->rootOffset);
+    window.y += value_Anim(&get_Window()->rootOffset);
 #endif
-    return bounds;
+    return window;
+}
+
+iInt2 windowToLocal_Widget(const iWidget *d, iInt2 windowCoord) {
+    iInt2 local = windowCoord;
+    for (const iWidget *w = d->parent; w; w = w->parent) {
+        subv_I2(&local, w->rect.pos);
+    }
+    return local;
 }
 
 iRect boundsWithoutVisualOffset_Widget(const iWidget *d) {
@@ -695,25 +709,32 @@ iRect boundsWithoutVisualOffset_Widget(const iWidget *d) {
     return bounds;
 }
 
-iInt2 localCoord_Widget(const iWidget *d, iInt2 coord) {
+iInt2 innerToWindow_Widget(const iWidget *d, iInt2 innerCoord) {
+    for (const iWidget *w = d; w; w = w->parent) {
+        addv_I2(&innerCoord, w->rect.pos);
+    }
+    return innerCoord;
+}
+
+iInt2 windowToInner_Widget(const iWidget *d, iInt2 windowCoord) {
     for (const iWidget *w = d; w; w = w->parent) {
-        subv_I2(&coord, w->rect.pos);
+        subv_I2(&windowCoord, w->rect.pos);
     }
-    return coord;
+    return windowCoord;
 }
 
-iBool contains_Widget(const iWidget *d, iInt2 coord) {
-    return containsExpanded_Widget(d, coord, 0);
+iBool contains_Widget(const iWidget *d, iInt2 windowCoord) {
+    return containsExpanded_Widget(d, windowCoord, 0);
 }
 
-iBool containsExpanded_Widget(const iWidget *d, iInt2 coord, int expand) {
+iBool containsExpanded_Widget(const iWidget *d, iInt2 windowCoord, int expand) {
     const iRect bounds = {
         zero_I2(),
         addY_I2(d->rect.size,
                 d->flags & drawBackgroundToBottom_WidgetFlag ? size_Root(d->root).y : 0)
     };
     return contains_Rect(expand ? expanded_Rect(bounds, init1_I2(expand)) : bounds,
-                         localCoord_Widget(d, coord));
+                         windowToInner_Widget(d, windowCoord));
 }
 
 iLocalDef iBool isKeyboardEvent_(const SDL_Event *ev) {
@@ -738,20 +759,15 @@ static iBool filterEvent_Widget_(const iWidget *d, const SDL_Event *ev) {
 }
 
 void unhover_Widget(void) {
-    /* TODO: Which root? */
-    get_Root()->hover = NULL;
+    get_Window()->hover = NULL;
 }
 
 iBool dispatchEvent_Widget(iWidget *d, const SDL_Event *ev) {
     iAssert(d->root == get_Root());
     if (!d->parent) {
-        if (ev->type == SDL_MOUSEMOTION) {
-            /* Hover widget may change. */
-            setHover_Widget(NULL);
-        }
-        if (d->root->focus && isKeyboardEvent_(ev)) {
+        if (get_Window()->focus && get_Window()->focus->root == d->root && isKeyboardEvent_(ev)) {
             /* Root dispatches keyboard events directly to the focused widget. */
-            if (dispatchEvent_Widget(d->root->focus, ev)) {
+            if (dispatchEvent_Widget(get_Window()->focus, ev)) {
                 return iTrue;
             }
         }
@@ -780,7 +796,7 @@ iBool dispatchEvent_Widget(iWidget *d, const SDL_Event *ev) {
         }
     }
     else if (ev->type == SDL_MOUSEMOTION &&
-             (!d->root->hover || hasParent_Widget(d, d->root->hover)) &&
+             (!get_Window()->hover || hasParent_Widget(d, get_Window()->hover)) &&
              flags_Widget(d) & hover_WidgetFlag && ~flags_Widget(d) & hidden_WidgetFlag &&
              ~flags_Widget(d) & disabled_WidgetFlag) {
         if (contains_Widget(d, init_I2(ev->motion.x, ev->motion.y))) {
@@ -798,7 +814,8 @@ iBool dispatchEvent_Widget(iWidget *d, const SDL_Event *ev) {
            handle the events first. */
         iReverseForEach(ObjectList, i, d->children) {
             iWidget *child = as_Widget(i.object);
-            if (child == d->root->focus && isKeyboardEvent_(ev)) {
+            iAssert(child->root == d->root);
+            if (child == get_Window()->focus && isKeyboardEvent_(ev)) {
                 continue; /* Already dispatched. */
             }
             if (isVisible_Widget(child) && child->flags & keepOnTop_WidgetFlag) {
@@ -870,7 +887,7 @@ static iBool scrollOverflow_Widget_(iWidget *d, int delta) {
 //    else {
 //        bounds.pos.y = iMax(bounds.pos.y, );
 //    }
-    const iInt2 newPos = localCoord_Widget(d->parent, bounds.pos);
+    const iInt2 newPos = windowToInner_Widget(d->parent, bounds.pos);
     if (!isEqual_I2(newPos, d->rect.pos)) {
         d->rect.pos = newPos;
         refresh_Widget(d);
@@ -1087,6 +1104,7 @@ iAny *addChildPosFlags_Widget(iWidget *d, iAnyObject *child, enum iWidgetAddPos
     iAssert(child);
     iAssert(d != child);
     iWidget *widget = as_Widget(child);
+    iAssert(widget->root == d->root);
     iAssert(!widget->parent);
     if (!d->children) {
         d->children = new_ObjectList();
@@ -1268,12 +1286,12 @@ iBool isDisabled_Widget(const iAnyObject *d) {
 
 iBool isFocused_Widget(const iAnyObject *d) {
     iAssert(isInstance_Object(d, &Class_Widget));
-    return ((const iWidget *) d)->root->focus == d;
+    return get_Window()->focus == d;
 }
 
 iBool isHover_Widget(const iAnyObject *d) {
     iAssert(isInstance_Object(d, &Class_Widget));
-    return ((const iWidget *) d)->root->hover == d;
+    return get_Window()->hover == d;
 }
 
 iBool isSelected_Widget(const iAnyObject *d) {
@@ -1319,15 +1337,14 @@ iBool isAffectedByVisualOffset_Widget(const iWidget *d) {
 }
 
 void setFocus_Widget(iWidget *d) {
-    iRoot *root = d ? d->root : get_Root();
-    if (root->focus != d) {
-        if (root->focus) {
-            iAssert(!contains_PtrSet(root->pendingDestruction, root->focus));
-            postCommand_Widget(root->focus, "focus.lost");
+    iWindow *win = get_Window();
+    if (win->focus != d) {
+        if (win->focus) {
+            iAssert(!contains_PtrSet(win->focus->root->pendingDestruction, win->focus));
+            postCommand_Widget(win->focus, "focus.lost");
         }
-        root->focus = d;
+        win->focus = d;
         if (d) {
-            iAssert(root == d->root);
             iAssert(flags_Widget(d) & focusable_WidgetFlag);
             postCommand_Widget(d, "focus.gained");
         }
@@ -1335,20 +1352,15 @@ void setFocus_Widget(iWidget *d) {
 }
 
 iWidget *focus_Widget(void) {
-    return get_Root()->focus;
+    return get_Window()->focus;
 }
 
 void setHover_Widget(iWidget *d) {
-    if (d) {
-        d->root->hover = d;
-    }
-    else {
-        get_Root()->hover = NULL;
-    }
+    get_Window()->hover = d;
 }
 
 iWidget *hover_Widget(void) {
-    return get_Root()->hover;
+    return get_Window()->hover;
 }
 
 static const iWidget *findFocusable_Widget_(const iWidget *d, const iWidget *startFrom,
@@ -1404,21 +1416,14 @@ iAny *findFocusable_Widget(const iWidget *startFrom, enum iWidgetFocusDir focusD
 }
 
 void setMouseGrab_Widget(iWidget *d) {
-    iRoot *root = d ? d->root : get_Root();
-    if (root->mouseGrab != d) {
-        root->mouseGrab = d;
+    if (get_Window()->mouseGrab != d) {
+        get_Window()->mouseGrab = d;
         SDL_CaptureMouse(d != NULL);
     }
 }
 
 iWidget *mouseGrab_Widget(void) {
-    iWindow *win = get_Window();    
-    iForIndices(i, win->roots) {
-        if (win->roots[i] && win->roots[i]->mouseGrab) {
-            return win->roots[i]->mouseGrab;            
-        }
-    }
-    return NULL;
+    return get_Window()->mouseGrab;
 }
 
 void postCommand_Widget(const iAnyObject *d, const char *cmd, ...) {
@@ -1438,7 +1443,7 @@ void postCommand_Widget(const iAnyObject *d, const char *cmd, ...) {
         iAssert(isInstance_Object(d, &Class_Widget));
         appendFormat_String(&str, " ptr:%p", d);
     }
-    postCommandString_App(&str);
+    postCommandString_Root(((const iWidget *) d)->root, &str);
     deinit_String(&str);
 }
 
diff --git a/src/ui/widget.h b/src/ui/widget.h
index f126d40d..2ef035b6 100644
--- a/src/ui/widget.h
+++ b/src/ui/widget.h
@@ -169,16 +169,24 @@ void    destroy_Widget          (iWidget *); /* widget removed and deleted later
 void    destroyPending_Widget   (void);
 void    releaseChildren_Widget  (iWidget *);
 
+/* Coordinate spaces:
+    - window: 0,0 is at the top left corner of the window
+    - local:  0,0 is at the top left corner of the parent widget
+    - inner:  0,0 is at the top left corner of the widget */
+
 iWidget *       root_Widget             (const iWidget *);
 const iString * id_Widget               (const iWidget *);
 int64_t flags_Widget                    (const iWidget *);
 iRect   bounds_Widget                   (const iWidget *); /* outer bounds */
 iRect   innerBounds_Widget              (const iWidget *);
 iRect   boundsWithoutVisualOffset_Widget(const iWidget *);
-iInt2   localCoord_Widget               (const iWidget *, iInt2 coord);
-iBool   contains_Widget                 (const iWidget *, iInt2 coord);
-iBool   containsExpanded_Widget         (const iWidget *, iInt2 coord, int expand);
-iAny *  hitChild_Widget                 (const iWidget *, iInt2 coord);
+iInt2   localToWindow_Widget            (const iWidget *, iInt2 localCoord);
+iInt2   windowToLocal_Widget            (const iWidget *, iInt2 windowCoord);
+iInt2   innerToWindow_Widget            (const iWidget *, iInt2 innerCoord);
+iInt2   windowToInner_Widget            (const iWidget *, iInt2 windowCoord);
+iBool   contains_Widget                 (const iWidget *, iInt2 windowCoord);
+iBool   containsExpanded_Widget         (const iWidget *, iInt2 windowCoord, int expand);
+iAny *  hitChild_Widget                 (const iWidget *, iInt2 windowCoord);
 iAny *  findChild_Widget                (const iWidget *, const char *id);
 const iPtrArray *findChildren_Widget    (const iWidget *, const char *id);
 iAny *  findParentClass_Widget          (const iWidget *, const iAnyClass *class);
diff --git a/src/ui/window.c b/src/ui/window.c
index e47b579f..78ea182c 100644
--- a/src/ui/window.c
+++ b/src/ui/window.c
@@ -189,8 +189,11 @@ static void windowSizeChanged_Window_(iWindow *d) {
         iRoot *root = d->roots[i];
         if (root) {
             root->widget->rect.pos  = init_I2(rootSize.x * i, 0);
-            root->widget->rect.size = rootSize; /* Reposition roots. */
-            root->widget->minSize   = rootSize;
+            root->widget->rect.size = addX_I2(rootSize, -gap_UI / 4);
+            if (i == 1) {
+                root->widget->rect.pos.x += gap_UI / 8;
+            }
+            root->widget->minSize   = root->widget->rect.size;
             updatePadding_Root(root);
             arrange_Widget(root->widget);
         }
@@ -220,7 +223,7 @@ static void updateSize_Window_(iWindow *d, iBool notifyAlways) {
 void drawWhileResizing_Window(iWindow *d, int w, int h) {
     /* This is called while a window resize is in progress, so we can be pretty confident
        the size has actually changed. */
-    d->size = init_I2(w, h);
+    d->size = coord_Window(d, w, h);
     windowSizeChanged_Window_(d);
     draw_Window(d);
 }
@@ -274,7 +277,8 @@ static float displayScale_Window_(const iWindow *d) {
 }
 
 static void drawBlank_Window_(iWindow *d) {
-    const iColor bg = get_Color(uiBackground_ColorId);
+//    const iColor bg = get_Color(uiBackground_ColorId);
+    const iColor bg = { 128, 128, 128, 255 }; /* TODO: Have no root yet. */
     SDL_SetRenderDrawColor(d->render, bg.r, bg.g, bg.b, 255);
     SDL_RenderClear(d->render);
     SDL_RenderPresent(d->render);
@@ -373,6 +377,9 @@ void init_Window(iWindow *d, iRect rect) {
     d->win = NULL;
     d->size = zero_I2(); /* will be updated below */
     iZap(d->roots);
+    d->hover = NULL;
+    d->mouseGrab = NULL;
+    d->focus = NULL;
     iZap(d->cursors);
     d->place.initialPos = rect.pos;
     d->place.normalRect = rect;
@@ -520,7 +527,6 @@ iRoot *findRoot_Window(const iWindow *d, const iWidget *widget) {
             return d->roots[i];
         }
     }
-    iAssert(iFalse); /* it must be under some Root */
     return NULL;
 }
 
@@ -811,10 +817,7 @@ iBool processEvent_Window(iWindow *d, const SDL_Event *ev) {
                 event.button.x = pos.x;
                 event.button.y = pos.y;
             }
-            const iWidget *oldHovers[2] = {
-                d->roots[0]->hover,
-                d->roots[1]->hover,
-            };
+            const iWidget *oldHover = d->hover;
             iBool wasUsed = iFalse;
             /* Dispatch first to the mouse-grabbed widget. */
 //            iWidget *widget = d->root.widget;
@@ -866,7 +869,7 @@ iBool processEvent_Window(iWindow *d, const SDL_Event *ev) {
                     }
                 }
             }
-            if (oldHovers[0] != d->roots[0]->hover || oldHovers[1] != d->roots[1]->hover) {
+            if (oldHover != d->hover) {
                 postRefresh_App();
             }
             if (event.type == SDL_MOUSEMOTION) {
@@ -879,9 +882,15 @@ iBool processEvent_Window(iWindow *d, const SDL_Event *ev) {
 }
 
 iBool dispatchEvent_Window(iWindow *d, const SDL_Event *ev) {
-    /* TODO: Dispatch to input-focused root first. */
+    if (ev->type == SDL_MOUSEMOTION) {
+        /* Hover widget may change. */
+        setHover_Widget(NULL);
+    }
     iForIndices(i, d->roots) {
         if (d->roots[i]) {
+            if (isCommand_SDLEvent(ev) && ev->user.data2 && ev->user.data2 != d->roots[i]) {
+                continue; /* Not meant for this root. */
+            }
             setCurrent_Root(d->roots[i]);
             const iBool wasUsed = dispatchEvent_Widget(d->roots[i]->widget, ev);
             if (wasUsed) {
diff --git a/src/ui/window.h b/src/ui/window.h
index 12c540d3..de0133b1 100644
--- a/src/ui/window.h
+++ b/src/ui/window.h
@@ -68,6 +68,9 @@ struct Impl_Window {
     SDL_Renderer *render;
     iInt2         size;
     iRoot *       roots[2];     /* root widget and UI state; second one is for split mode */
+    iWidget *     hover;
+    iWidget *     mouseGrab;
+    iWidget *     focus;
     float         pixelRatio;   /* conversion between points and pixels, e.g., coords, window size */
     float         displayScale; /* DPI-based scaling factor of current display, affects uiScale only */
     float         uiScale;