6 files changed, 117 insertions, 16 deletions

diff --git a/src/app.c b/src/app.c
index f909c251..4872799b 100644
--- a/src/app.c
+++ b/src/app.c
@@ -2109,6 +2109,7 @@ iBool handleCommand_App(const char *cmd) {
         iBool  wasCurrent = (doc == (iWidget *) document_App());
         size_t index      = tabPageIndex_Widget(tabs, doc);
         iBool  wasClosed  = iFalse;
+        postCommand_App("document.openurls.changed");
         if (argLabel_Command(cmd, "toright")) {
             while (tabCount_Widget(tabs) > index + 1) {
                 destroy_Widget(removeTabPage_Widget(tabs, index + 1));
@@ -2314,6 +2315,11 @@ iBool handleCommand_App(const char *cmd) {
         save_Visited(d->visited, dataDir_App_());
         return iFalse;
     }
+    else if (equal_Command(cmd, "document.changed")) {
+        /* Set of open tabs has changed. */
+        postCommand_App("document.openurls.changed");
+        return iFalse;
+    }
     else if (equal_Command(cmd, "ident.new")) {
         iWidget *dlg = makeIdentityCreation_Widget();
         setFocus_Widget(findChild_Widget(dlg, "ident.until"));
@@ -2472,3 +2478,13 @@ iObjectList *listDocuments_App(const iRoot *rootOrNull) {
     }
     return docs;
 }
+
+iStringSet *listOpenURLs_App(void) {
+    iStringSet *set = new_StringSet();
+    iObjectList *docs = listDocuments_App(NULL);
+    iConstForEach(ObjectList, i, docs) {
+        insert_StringSet(set, withSpacesEncoded_String(url_DocumentWidget(i.object)));
+    }
+    iRelease(docs);
+    return set;
+}
diff --git a/src/app.h b/src/app.h
index 952688a4..c8f0f1c2 100644
--- a/src/app.h
+++ b/src/app.h
@@ -26,6 +26,7 @@ SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE. */
 
 #include <the_Foundation/objectlist.h>
 #include <the_Foundation/string.h>
+#include <the_Foundation/stringset.h>
 #include <the_Foundation/time.h>
 
 #include "prefs.h"
@@ -90,6 +91,7 @@ iMimeHooks *        mimeHooks_App       (void);
 iPeriodic *         periodic_App        (void);
 iDocumentWidget *   document_App        (void);
 iObjectList *       listDocuments_App   (const iRoot *rootOrNull); /* NULL for all roots */
+iStringSet *        listOpenURLs_App    (void); /* all tabs */
 iDocumentWidget *   newTab_App          (const iDocumentWidget *duplicateOf, iBool switchToNew);
 void                trimCache_App       (void);
 
diff --git a/src/gmdocument.c b/src/gmdocument.c
index 47f629bd..b64e9ea7 100644
--- a/src/gmdocument.c
+++ b/src/gmdocument.c
@@ -33,6 +33,7 @@ SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE. */
 
 #include <the_Foundation/ptrarray.h>
 #include <the_Foundation/regexp.h>
+#include <the_Foundation/stringset.h>
 
 #include <ctype.h>
 
@@ -87,6 +88,7 @@ struct Impl_GmDocument {
     uint32_t  themeSeed;
     iChar     siteIcon;
     iMedia *  media;
+    iStringSet *openURLs; /* currently open URLs for highlighting links */
 };
 
 iDefineObjectConstruction(GmDocument)
@@ -229,6 +231,9 @@ static iRangecc addLink_GmDocument_(iGmDocument *d, iRangecc line, iGmLinkId *li
                 if (isValid_Time(&link->when)) {
                     link->flags |= visited_GmLinkFlag;
                 }
+                if (contains_StringSet(d->openURLs, &link->url)) {
+                    link->flags |= isOpen_GmLinkFlag;
+                }
             }
         }
         pushBack_PtrArray(&d->links, link);
@@ -340,6 +345,13 @@ static void alignDecoration_GmRun_(iGmRun *run, iBool isCentered) {
     run->visBounds.size.x -= xAdjust;
 }
 
+static void updateOpenURLs_GmDocument_(iGmDocument *d) {
+    if (d->openURLs) {
+        iReleasePtr(&d->openURLs);
+    }
+    d->openURLs = listOpenURLs_App();
+}
+
 static void doLayout_GmDocument_(iGmDocument *d) {
     const iPrefs *prefs             = prefs_App();
     const iBool   isMono            = isForcedMonospace_GmDocument_(d);
@@ -405,6 +417,7 @@ static void doLayout_GmDocument_(iGmDocument *d) {
     if (d->size.x <= 0 || isEmpty_String(&d->source)) {
         return;
     }
+    updateOpenURLs_GmDocument_(d);
     const iRangecc   content       = range_String(&d->source);
     iRangecc         contentLine   = iNullRange;
     iInt2            pos           = zero_I2();
@@ -861,9 +874,11 @@ void init_GmDocument(iGmDocument *d) {
     d->themeSeed = 0;
     d->siteIcon = 0;
     d->media = new_Media();
+    d->openURLs = NULL;
 }
 
 void deinit_GmDocument(iGmDocument *d) {
+    iReleasePtr(&d->openURLs);
     delete_Media(d->media);
     deinit_String(&d->bannerText);
     deinit_String(&d->title);
@@ -900,10 +915,15 @@ static void setDerivedThemeColors_(enum iGmDocumentTheme theme) {
     set_Color(tmQuoteIcon_ColorId,
               mix_Color(get_Color(tmQuote_ColorId), get_Color(tmBackground_ColorId), 0.55f));
     set_Color(tmBannerSideTitle_ColorId,
-              mix_Color(get_Color(tmBannerTitle_ColorId), get_Color(tmBackground_ColorId),
+              mix_Color(get_Color(tmBannerTitle_ColorId),
+                        get_Color(tmBackground_ColorId),
                         theme == colorfulDark_GmDocumentTheme ? 0.55f : 0));
-    set_Color(tmAltTextBackground_ColorId, mix_Color(get_Color(tmQuoteIcon_ColorId),
-                                                     get_Color(tmBackground_ColorId), 0.85f));
+    set_Color(tmBackgroundAltText_ColorId,
+              mix_Color(get_Color(tmQuoteIcon_ColorId), get_Color(tmBackground_ColorId), 0.85f));
+    set_Color(tmBackgroundOpenLink_ColorId,
+              mix_Color(get_Color(tmLinkText_ColorId), get_Color(tmBackground_ColorId), 0.92f));
+    set_Color(tmFrameOpenLink_ColorId,
+              mix_Color(get_Color(tmLinkText_ColorId), get_Color(tmBackground_ColorId), 0.78f));
     if (theme == colorfulDark_GmDocumentTheme) {
         /* Ensure paragraph text and link text aren't too similarly colored. */
         if (delta_Color(get_Color(tmLinkText_ColorId), get_Color(tmParagraph_ColorId)) < 100) {
@@ -1381,6 +1401,22 @@ void redoLayout_GmDocument(iGmDocument *d) {
     doLayout_GmDocument_(d);
 }
 
+iBool updateOpenURLs_GmDocument(iGmDocument *d) {
+    iBool wasChanged = iFalse;
+    updateOpenURLs_GmDocument_(d);
+    iForEach(PtrArray, i, &d->links) {
+        iGmLink *link = i.ptr;
+        if (!equal_String(&link->url, &d->url)) {
+            const iBool isOpen = contains_StringSet(d->openURLs, &link->url);
+            if (isOpen ^ ((link->flags & isOpen_GmLinkFlag) != 0)) {
+                iChangeFlags(link->flags, isOpen_GmLinkFlag, isOpen);
+                wasChanged = iTrue;
+            }
+        }
+    }
+    return wasChanged;
+}
+
 iLocalDef iBool isNormalizableSpace_(char ch) {
     return ch == ' ' || ch == '\t';
 }
diff --git a/src/gmdocument.h b/src/gmdocument.h
index 5d34dbaf..574f0acf 100644
--- a/src/gmdocument.h
+++ b/src/gmdocument.h
@@ -83,6 +83,7 @@ enum iGmLinkFlags {
     permanent_GmLinkFlag          = iBit(15), /* content cannot be dismissed; media link */
     query_GmLinkFlag              = iBit(16), /* Gopher query link */
     iconFromLabel_GmLinkFlag      = iBit(17), /* use an Emoji/special character from label */
+    isOpen_GmLinkFlag             = iBit(18), /* currently open in a tab */
 };
 
 struct Impl_GmHeading {
@@ -164,6 +165,7 @@ void    setFormat_GmDocument    (iGmDocument *, enum iGmDocumentFormat format);
 void    setBanner_GmDocument    (iGmDocument *, enum iGmDocumentBanner type);
 void    setWidth_GmDocument     (iGmDocument *, int width);
 void    redoLayout_GmDocument   (iGmDocument *);
+iBool   updateOpenURLs_GmDocument(iGmDocument *);
 void    setUrl_GmDocument       (iGmDocument *, const iString *url);
 void    setSource_GmDocument    (iGmDocument *, const iString *source, int width);
 void    foldPre_GmDocument      (iGmDocument *, uint16_t preId);
diff --git a/src/ui/color.h b/src/ui/color.h
index c0db4382..d2fa3c00 100644
--- a/src/ui/color.h
+++ b/src/ui/color.h
@@ -132,7 +132,9 @@ enum iColorId {
     tmBannerIcon_ColorId,
     tmBannerSideTitle_ColorId,
     tmInlineContentMetadata_ColorId,
-    tmAltTextBackground_ColorId,     /* derived from other theme colors */
+    tmBackgroundAltText_ColorId,     /* derived from other theme colors */
+    tmBackgroundOpenLink_ColorId,    /* derived from other theme colors */
+    tmFrameOpenLink_ColorId,         /* derived from other theme colors */
     tmLinkCustomIconVisited_ColorId, /* derived from other theme colors */
     tmBadLink_ColorId,
 
diff --git a/src/ui/documentwidget.c b/src/ui/documentwidget.c
index 16d2a84a..6a44fd5f 100644
--- a/src/ui/documentwidget.c
+++ b/src/ui/documentwidget.c
@@ -286,7 +286,7 @@ struct Impl_DocumentWidget {
     iWidget *      playerMenu;
     iWidget *      copyMenu;
     iVisBuf *      visBuf;
-    iGmRunRange *  visBufMeta;
+    iVisBufMeta *  visBufMeta;
     iPtrSet *      invalidRuns;
     iDrawBufs *    drawBufs; /* dynamic state for drawing */
     iTranslation * translation;
@@ -1881,7 +1881,15 @@ static iBool handlePinch_DocumentWidget_(iDocumentWidget *d, const char *cmd) {
 
 static iBool handleCommand_DocumentWidget_(iDocumentWidget *d, const char *cmd) {
     iWidget *w = as_Widget(d);
-    if (equal_Command(cmd, "document.render")) /* Periodic makes direct dispatch to here */ {
+    if (equal_Command(cmd, "document.openurls.changed")) {
+        /* When any tab changes its document URL, update the open link indicators. */
+        if (updateOpenURLs_GmDocument(d->doc)) {
+            invalidate_DocumentWidget_(d);
+            refresh_Widget(d);
+        }
+        return iFalse;
+    }
+    if (equal_Command(cmd, "document.render")) /* `Periodic` makes direct dispatch to here */ {
 //        printf("%u: document.render\n", SDL_GetTicks());
         if (SDL_GetTicks() - d->drawBufs->lastRenderTime > 150) {
             remove_Periodic(periodic_App(), d);
@@ -3486,15 +3494,18 @@ static void drawRun_DrawContext_(void *context, const iGmRun *run) {
         /* Media UIs are drawn afterwards as a dynamic overlay. */
         return;
     }
-//    printf("  drawRun: {%s}\n", cstr_Rangecc(run->text));
-    enum iColorId      fg  = run->color;
-    const iGmDocument *doc = d->widget->doc;
-    iBool              isHover =
+    enum iColorId      fg        = run->color;
+    const iGmDocument *doc       = d->widget->doc;
+    const int          linkFlags = linkFlags_GmDocument(doc, run->linkId);
+    /* Hover state of a link. */
+    iBool isHover =
         (run->linkId && d->widget->hoverLink && run->linkId == d->widget->hoverLink->linkId &&
          ~run->flags & decoration_GmRunFlag);
+    /* Visible (scrolled) position of the run. */
     const iInt2 visPos = addX_I2(add_I2(run->visBounds.pos, origin),
                                  /* Preformatted runs can be scrolled. */
                                  runOffset_DocumentWidget_(d->widget, run));
+    const iRect visRect = { visPos, run->visBounds.size };
     if (run->flags & footer_GmRunFlag) {
         iRect footerBack =
             (iRect){ visPos, init_I2(width_Rect(d->widgetBounds), run->visBounds.size.y) };
@@ -3502,16 +3513,48 @@ static void drawRun_DrawContext_(void *context, const iGmRun *run) {
         fillRect_Paint(&d->paint, footerBack, tmBackground_ColorId);
         return;
     }
-    fillRect_Paint(&d->paint, (iRect){ visPos, run->visBounds.size }, tmBackground_ColorId);
+    /* Fill the background. */ {
+        if (run->linkId && linkFlags & isOpen_GmLinkFlag) {
+            /* Open links get a highlighted background. */
+            int bg = tmBackgroundOpenLink_ColorId;
+            const int frame = tmFrameOpenLink_ColorId;
+            iRect     wideRect = { init_I2(left_Rect(d->widgetBounds), visPos.y),
+                               init_I2(width_Rect(d->widgetBounds) +
+                                           width_Widget(d->widget->scroll),
+                                       height_Rect(run->visBounds)) };
+            /* The first line is composed of two runs that may be drawn in either order, so
+               only draw half of the background. */
+            if (run->flags & decoration_GmRunFlag) {
+                wideRect.size.x = right_Rect(visRect) - left_Rect(wideRect);
+            }
+            else if (run->flags & startOfLine_GmRunFlag) {
+                wideRect.size.x = right_Rect(wideRect) - left_Rect(visRect);
+                wideRect.pos.x  = left_Rect(visRect);
+            }
+            fillRect_Paint(&d->paint, wideRect, bg);
+            if (run->flags & (startOfLine_GmRunFlag | decoration_GmRunFlag)) {
+                drawHLine_Paint(&d->paint, topLeft_Rect(wideRect), width_Rect(wideRect), frame);
+            }
+            /* TODO: The decoration is not marked as endOfLine, so it lacks the bottom line. */
+//            if (run->flags & endOfLine_GmRunFlag) {
+//                drawHLine_Paint(
+//                    &d->paint, addY_I2(bottomLeft_Rect(wideRect), -1), width_Rect(wideRect), frame);
+//            }
+        }
+        else {
+            /* Normal background for other runs. */
+            fillRect_Paint(&d->paint, (iRect){ visPos, run->visBounds.size }, tmBackground_ColorId);
+        }
+    }
     if (run->linkId && ~run->flags & decoration_GmRunFlag) {
         fg = linkColor_GmDocument(doc, run->linkId, isHover ? textHover_GmLinkPart : text_GmLinkPart);
-        if (linkFlags_GmDocument(doc, run->linkId) & content_GmLinkFlag) {
+        if (linkFlags & content_GmLinkFlag) {
             fg = linkColor_GmDocument(doc, run->linkId, textHover_GmLinkPart); /* link is inactive */
         }
     }
     if (run->flags & altText_GmRunFlag) {
         const iInt2 margin = preRunMargin_GmDocument(doc, run->preId);
-        fillRect_Paint(&d->paint, (iRect){ visPos, run->visBounds.size }, tmAltTextBackground_ColorId);
+        fillRect_Paint(&d->paint, (iRect){ visPos, run->visBounds.size }, tmBackgroundAltText_ColorId);
         drawRect_Paint(&d->paint, (iRect){ visPos, run->visBounds.size }, tmQuoteIcon_ColorId);
         drawWrapRange_Text(run->font, add_I2(visPos, margin),
                            run->visBounds.size.x - 2 * margin.x, run->color, run->text);
@@ -3552,7 +3595,7 @@ static void drawRun_DrawContext_(void *context, const iGmRun *run) {
     if (run->linkId && ~run->flags & decoration_GmRunFlag) {
         const int metaFont = paragraph_FontId;
         /* TODO: Show status of an ongoing media request. */
-        const int flags = linkFlags_GmDocument(doc, run->linkId);
+        const int flags = linkFlags;
         const iRect linkRect = moved_Rect(run->visBounds, origin);
         iMediaRequest *mr = NULL;
         /* Show metadata about inline content. */
@@ -3614,7 +3657,7 @@ static void drawRun_DrawContext_(void *context, const iGmRun *run) {
         else if (isHover) {
             const iGmLinkId linkId = d->widget->hoverLink->linkId;
             const iString * url    = linkUrl_GmDocument(doc, linkId);
-            const int       flags  = linkFlags_GmDocument(doc, linkId);
+            const int       flags  = linkFlags;
             iUrl parts;
             init_Url(&parts, url);
             fg                    = linkColor_GmDocument(doc, linkId, textHover_GmLinkPart);
@@ -4122,7 +4165,7 @@ static void draw_DocumentWidget_(const iDocumentWidget *d) {
             if (altTextOpacity < 1) {
                 SDL_SetRenderDrawBlendMode(renderer_Window(get_Window()), SDL_BLENDMODE_BLEND);
             }
-            fillRect_Paint(&ctx.paint, altRect, tmAltTextBackground_ColorId);
+            fillRect_Paint(&ctx.paint, altRect, tmBackgroundAltText_ColorId);
             drawRect_Paint(&ctx.paint, altRect, tmQuoteIcon_ColorId);
             setOpacity_Text(altTextOpacity);
             drawWrapRange_Text(altFont, addX_I2(pos, margin), wrap,