relanding bug 118312 since it doesn't look to be the source of the Ts regression

toolkit/themes/gnomestripe/global/tree.css

@@ -171,19 +171,6 @@ tree[seltype="text"] > treechildren::-moz-tree-cell-text(active, selected, curre
   border: 1px dotted #C0C0C0;
 }
 
-/* ::::: lines connecting cells ::::: */
-
-tree[seltype="cell"] > treechildren::-moz-tree-line,
-tree[seltype="text"] > treechildren::-moz-tree-line,
-treechildren::-moz-tree-line {
-  border: 1px dotted ThreeDShadow;
-}
-
-tree[seltype="cell"] > treechildren::-moz-tree-line(active, selected, focus),
-treechildren::-moz-tree-line(selected, focus) {
-  border: 1px dotted HighlightText;
-}
-
 
 /* ::::: tree separator ::::: */
 
@@ -323,6 +310,7 @@ treechildren::-moz-tree-column(insertafter) {
 /* ::::: twisty :::::  */
 
 treechildren::-moz-tree-twisty {
+  -moz-appearance: treetwisty;
   padding-right: 4px;
   padding-top: 1px;
   width: 9px; /* The image's width is 9 pixels */
@@ -330,6 +318,7 @@ treechildren::-moz-tree-twisty {
 }
 
 treechildren::-moz-tree-twisty(open) {
+  -moz-appearance: treetwistyopen;
   width: 9px; /* The image's width is 9 pixels */
   list-style-image: url("chrome://global/skin/tree/twisty-open.png");
 }

widget/src/gtk2/gtk2drawing.c

@@ -81,6 +81,7 @@ static GtkWidget* gCheckMenuItemWidget;
 static GtkWidget* gTreeViewWidget;
 static GtkWidget* gTreeHeaderCellWidget;
 static GtkWidget* gTreeHeaderSortArrowWidget;
+static GtkWidget* gExpanderWidget;
 
 static GtkShadowType gMenuBarShadowType;
 static GtkShadowType gToolbarShadowType;
@@ -378,6 +379,16 @@ ensure_tree_header_cell_widget()
     return MOZ_GTK_SUCCESS;
 }
 
+static gint
+ensure_expander_widget()
+{
+    if (!gExpanderWidget) {
+        gExpanderWidget = gtk_expander_new("M");
+        setup_widget_prototype(gExpanderWidget);
+    }
+    return MOZ_GTK_SUCCESS;
+}
+
 static GtkStateType
 ConvertGtkState(GtkWidgetState* state)
 {
@@ -1080,6 +1091,28 @@ moz_gtk_tree_header_sort_arrow_paint(GdkDrawable* drawable, GdkRectangle* rect,
     return MOZ_GTK_SUCCESS;
 }
 
+static gint
+moz_gtk_expander_paint(GdkDrawable* drawable, GdkRectangle* rect,
+                       GdkRectangle* cliprect, GtkWidgetState* state,
+                       GtkExpanderStyle expander_state)
+{
+    GtkStyle *style;
+    GtkStateType state_type;
+
+    ensure_expander_widget();
+    style = gExpanderWidget->style;
+
+    /* Because the frame we get is of the entire treeview, we can't get the precise
+     * event state of one expander, thus rendering hover and active feedback useless. */
+    state_type = state->disabled ? GTK_STATE_INSENSITIVE : GTK_STATE_NORMAL;
+
+    TSOffsetStyleGCs(style, rect->x, rect->y);
+    gtk_paint_expander(style, drawable, state_type, cliprect, gExpanderWidget, "expander",
+                       rect->x + rect->width / 2, rect->y + rect->height / 2, expander_state);
+
+    return MOZ_GTK_SUCCESS;
+}
+
 static gint
 moz_gtk_option_menu_paint(GdkDrawable* drawable, GdkRectangle* rect,
                           GdkRectangle* cliprect, GtkWidgetState* state)
@@ -1823,6 +1856,7 @@ moz_gtk_get_widget_border(GtkThemeWidgetType widget, gint* left, gint* top,
     case MOZ_GTK_GRIPPER:
     case MOZ_GTK_PROGRESS_CHUNK:
     case MOZ_GTK_TAB:
+    case MOZ_GTK_EXPANDER:
     /* These widgets have no borders.*/
     case MOZ_GTK_TOOLTIP:
     case MOZ_GTK_WINDOW:
@@ -1860,6 +1894,17 @@ moz_gtk_get_dropdown_arrow_size(gint* width, gint* height)
     return MOZ_GTK_SUCCESS;
 }
 
+gint
+moz_gtk_get_expander_size(gint* size)
+{
+    ensure_expander_widget();
+    gtk_widget_style_get(gExpanderWidget,
+                         "expander-size", size,
+                         NULL);
+
+    return MOZ_GTK_SUCCESS;
+}
+
 gint
 moz_gtk_get_scalethumb_metrics(GtkOrientation orient, gint* thumb_length, gint* thumb_height)
 {
@@ -1950,6 +1995,9 @@ moz_gtk_widget_paint(GtkThemeWidgetType widget, GdkDrawable* drawable,
     case MOZ_GTK_TREE_HEADER_SORTARROW:
         return moz_gtk_tree_header_sort_arrow_paint(drawable, rect, cliprect, state, (GtkArrowType) flags);
         break;
+    case MOZ_GTK_EXPANDER:
+        return moz_gtk_expander_paint(drawable, rect, cliprect, state, (GtkExpanderStyle) flags);
+        break;
     case MOZ_GTK_ENTRY:
         return moz_gtk_entry_paint(drawable, rect, cliprect, state);
         break;
@@ -2060,6 +2108,7 @@ moz_gtk_shutdown()
     gTreeViewWidget = NULL;
     gTreeHeaderCellWidget = NULL;
     gTreeHeaderSortArrowWidget = NULL;
+    gExpanderWidget = NULL;
 
     is_initialized = FALSE;
 

widget/src/gtk2/gtkdrawing.h

@@ -159,6 +159,8 @@ typedef enum {
   MOZ_GTK_TREE_HEADER_CELL,
   /* Paints sort arrows in treeheader cells */
   MOZ_GTK_TREE_HEADER_SORTARROW,
+  /* Paints a GtkExpander for treeviews */
+  MOZ_GTK_EXPANDER,
   /* Paints the background of the menu bar. */
   MOZ_GTK_MENUBAR,
   /* Paints the background of menus, context menus. */
@@ -291,6 +293,14 @@ moz_gtk_get_scrollbar_metrics(MozGtkScrollbarMetrics* metrics);
  */
 gint moz_gtk_get_dropdown_arrow_size(gint* width, gint* height);
 
+/**
+ * Get the size of a treeview's expander (we call them twisties)
+ * size:    [OUT] the size of the GTK expander, size = width = height.
+ *
+ * returns:    MOZ_GTK_SUCCESS if there was no error, an error code otherwise
+ */
+gint moz_gtk_get_expander_size(gint* size);
+
 /**
  * Retrieve an actual GTK scrollbar widget for style analysis. It will not
  * be modified.

widget/src/gtk2/nsNativeThemeGTK.cpp

@@ -403,6 +403,16 @@ nsNativeThemeGTK::GetGtkWidgetAndState(PRUint8 aWidgetType, nsIFrame* aFrame,
     }
     aGtkWidgetType = MOZ_GTK_TREE_HEADER_SORTARROW;
     break;
+  case NS_THEME_TREEVIEW_TWISTY:
+    aGtkWidgetType = MOZ_GTK_EXPANDER;
+    if (aWidgetFlags)
+      *aWidgetFlags = GTK_EXPANDER_COLLAPSED;
+    break;
+  case NS_THEME_TREEVIEW_TWISTY_OPEN:
+    aGtkWidgetType = MOZ_GTK_EXPANDER;
+    if (aWidgetFlags)
+      *aWidgetFlags = GTK_EXPANDER_EXPANDED;
+    break;
   case NS_THEME_DROPDOWN:
     aGtkWidgetType = MOZ_GTK_DROPDOWN;
     break;
@@ -888,6 +898,16 @@ nsNativeThemeGTK::GetMinimumWidgetSize(nsIRenderingContext* aContext,
     // same as Windows to make our lives easier
     aResult->width = aResult->height = 15;
     break;
+  case NS_THEME_TREEVIEW_TWISTY:
+  case NS_THEME_TREEVIEW_TWISTY_OPEN:
+    {
+      gint expander_size;
+
+      moz_gtk_get_expander_size(&expander_size);
+      aResult->width = aResult->height = expander_size;
+      *aIsOverridable = PR_FALSE;
+    }
+    break;
   }
   return NS_OK;
 }
@@ -982,12 +1002,12 @@ nsNativeThemeGTK::ThemeSupportsWidget(nsPresContext* aPresContext,
     // case NS_THEME_LISTBOX_LISTITEM:
   case NS_THEME_TREEVIEW:
     // case NS_THEME_TREEVIEW_TREEITEM:
-    // case NS_THEME_TREEVIEW_TWISTY:
+  case NS_THEME_TREEVIEW_TWISTY:
     // case NS_THEME_TREEVIEW_LINE:
     // case NS_THEME_TREEVIEW_HEADER:
   case NS_THEME_TREEVIEW_HEADER_CELL:
   case NS_THEME_TREEVIEW_HEADER_SORTARROW:
-    // case NS_THEME_TREEVIEW_TWISTY_OPEN:
+  case NS_THEME_TREEVIEW_TWISTY_OPEN:
     case NS_THEME_PROGRESSBAR:
     case NS_THEME_PROGRESSBAR_CHUNK:
     case NS_THEME_PROGRESSBAR_VERTICAL: