[GTK3] Introduce MOZ_GTK_TEXT_VIEW_TEXT and move MOZ_GTK_RESIZER to WidgetStyleCache

The style context for MOZ_GTK_TEXT_VIEW is now created by copying from the widget instead of caching a widget and using its context.
No rendering changes are expected, unless themes are animating GtkTextView backgrounds.

widget/gtk/WidgetStyleCache.cpp

@@ -433,15 +433,6 @@ CreateScrolledWindowWidget()
   return widget;
 }
 
-static GtkWidget*
-CreateTextViewWidget()
-{
-  GtkWidget* widget = gtk_text_view_new();
-  gtk_container_add(GTK_CONTAINER(GetWidget(MOZ_GTK_SCROLLED_WINDOW)),
-                    widget);
-  return widget;
-}
-
 static GtkWidget*
 CreateMenuSeparatorWidget()
 {
@@ -591,8 +582,6 @@ CreateWidget(WidgetNodeType aWidgetType)
       return CreateEntryWidget();
     case MOZ_GTK_SCROLLED_WINDOW: 
       return CreateScrolledWindowWidget();
-    case MOZ_GTK_TEXT_VIEW:
-      return CreateTextViewWidget();
     case MOZ_GTK_TREEVIEW:
       return CreateTreeViewWidget();
     case MOZ_GTK_TREE_HEADER_CELL:
@@ -754,6 +743,10 @@ GetWidgetRootStyle(WidgetNodeType aNodeType)
       style = CreateStyleForWidget(gtk_radio_menu_item_new(nullptr),
                                    MOZ_GTK_MENUPOPUP);
       break;
+    case MOZ_GTK_TEXT_VIEW:
+      style = CreateStyleForWidget(gtk_text_view_new(),
+                                   MOZ_GTK_SCROLLED_WINDOW);
+      break;
     case MOZ_GTK_TOOLTIP:
       if (gtk_check_version(3, 20, 0) != nullptr) {
           // The tooltip style class is added first in CreateTooltipWidget()
@@ -881,10 +874,21 @@ GetCssNodeStyleInternal(WidgetNodeType aNodeType)
       // TODO - create from CSS node
       return GetWidgetStyleWithClass(MOZ_GTK_SCROLLED_WINDOW,
                                      GTK_STYLE_CLASS_FRAME);
-    case MOZ_GTK_TEXT_VIEW:
+    case MOZ_GTK_TEXT_VIEW_TEXT:
+    case MOZ_GTK_RESIZER:
       // TODO - create from CSS node
-      return GetWidgetStyleWithClass(MOZ_GTK_TEXT_VIEW,
-                                     GTK_STYLE_CLASS_VIEW);
+      style = GetWidgetStyleWithClass(MOZ_GTK_TEXT_VIEW, GTK_STYLE_CLASS_VIEW);
+      if (aNodeType == MOZ_GTK_RESIZER) {
+        // The "grip" class provides the correct builtin icon from
+        // gtk_render_handle().  The icon is drawn with shaded variants of
+        // the background color, and so a transparent background would lead to
+        // a transparent resizer.  gtk_render_handle() also uses the
+        // background color to draw a background, and so this style otherwise
+        // matches MOZ_GTK_TEXT_VIEW_TEXT to match the background with
+        // textarea elements.
+        gtk_style_context_add_class(style, GTK_STYLE_CLASS_GRIP);
+      }
+      return style;
     case MOZ_GTK_FRAME_BORDER:
       style = CreateChildCSSNode("border", MOZ_GTK_FRAME);
       break;
@@ -1008,9 +1012,25 @@ GetWidgetStyleInternal(WidgetNodeType aNodeType)
     case MOZ_GTK_SCROLLED_WINDOW:
       return GetWidgetStyleWithClass(MOZ_GTK_SCROLLED_WINDOW,
                                      GTK_STYLE_CLASS_FRAME);
-    case MOZ_GTK_TEXT_VIEW:
-      return GetWidgetStyleWithClass(MOZ_GTK_TEXT_VIEW,
-                                     GTK_STYLE_CLASS_VIEW);
+    case MOZ_GTK_TEXT_VIEW_TEXT:
+    case MOZ_GTK_RESIZER: {
+      // GTK versions prior to 3.20 do not have the view class on the root
+      // node, but add this to determine the background for the text window.
+      GtkStyleContext* style =
+        GetWidgetStyleWithClass(MOZ_GTK_TEXT_VIEW, GTK_STYLE_CLASS_VIEW);
+      if (aNodeType == MOZ_GTK_RESIZER) {
+        // The "grip" class provides the correct builtin icon from
+        // gtk_render_handle().  The icon is drawn with shaded variants of
+        // the background color, and so a transparent background would lead to
+        // a transparent resizer.  gtk_render_handle() also uses the
+        // background color to draw a background, and so this style otherwise
+        // matches MOZ_GTK_TEXT_VIEW_TEXT to match the background with
+        // textarea elements.  GtkTextView creates a separate text window and
+        // so the background should not be transparent.
+        gtk_style_context_add_class(style, GTK_STYLE_CLASS_GRIP);
+      }
+      return style;
+    }
     case MOZ_GTK_FRAME_BORDER:
       return GetWidgetRootStyle(MOZ_GTK_FRAME);
     case MOZ_GTK_TREEVIEW_VIEW:

widget/gtk/gtk3drawing.cpp

@@ -897,8 +897,10 @@ moz_gtk_text_view_paint(cairo_t *cr, GdkRectangle* rect,
     gtk_style_context_get_padding(style_frame, state_flags, &padding);
     ReleaseStyleContext(style_frame);
 
+     // There is a separate "text" window, which provides the background behind
+     // the text.
     GtkStyleContext* style =
-        ClaimStyleContext(MOZ_GTK_TEXT_VIEW, direction, state_flags);
+        ClaimStyleContext(MOZ_GTK_TEXT_VIEW_TEXT, direction, state_flags);
 
     gint xthickness = border.left + padding.left;
     gint ythickness = border.top + padding.top;
@@ -1337,17 +1339,9 @@ moz_gtk_resizer_paint(cairo_t *cr, GdkRectangle* rect,
                       GtkWidgetState* state,
                       GtkTextDirection direction)
 {
-    GtkStyleContext* style;
-
-    // gtk_render_handle() draws a background, so use GtkTextView and its
-    // GTK_STYLE_CLASS_VIEW to match the background with textarea elements.
-    // The resizer is drawn with shaded variants of the background color, and
-    // so a transparent background would lead to a transparent resizer.
-    style = ClaimStyleContext(MOZ_GTK_TEXT_VIEW, GTK_TEXT_DIR_LTR,
-                              GetStateFlagsFromGtkWidgetState(state));
-    // TODO - we need to save/restore style when gtk 3.20 CSS node path
-    // is used
-    gtk_style_context_add_class(style, GTK_STYLE_CLASS_GRIP);
+    GtkStyleContext* style =
+        ClaimStyleContext(MOZ_GTK_RESIZER, GTK_TEXT_DIR_LTR,
+                          GetStateFlagsFromGtkWidgetState(state));
 
     // Workaround unico not respecting the text direction for resizers.
     // See bug 1174248.

widget/gtk/gtkdrawing.h

@@ -145,8 +145,11 @@ typedef enum {
   MOZ_GTK_ENTRY,
   /* Paints a GtkExpander. */
   MOZ_GTK_EXPANDER,
-  /* Paints a GtkTextView. */
+  /* Paints a GtkTextView or gets the style context corresponding to the
+     root node of a GtkTextView. */
   MOZ_GTK_TEXT_VIEW,
+  /* The "text" window or node of a GtkTextView */
+  MOZ_GTK_TEXT_VIEW_TEXT,
   /* Paints a GtkOptionMenu. */
   MOZ_GTK_DROPDOWN,
   /* Paints a dropdown arrow (a GtkButton containing a down GtkArrow). */
@@ -168,7 +171,7 @@ typedef enum {
   MOZ_GTK_FRAME,
   /* Paints the border of a GtkFrame */
   MOZ_GTK_FRAME_BORDER,
-  /* Paints a resize grip for a GtkWindow */
+  /* Paints a resize grip for a GtkTextView */
   MOZ_GTK_RESIZER,
   /* Paints a GtkProgressBar. */
   MOZ_GTK_PROGRESSBAR,

widget/gtk/nsLookAndFeel.cpp

@@ -1291,7 +1291,7 @@ nsLookAndFeel::Init()
     }
 #else
     // Text colors
-    style = ClaimStyleContext(MOZ_GTK_TEXT_VIEW);
+    style = ClaimStyleContext(MOZ_GTK_TEXT_VIEW_TEXT);
     gtk_style_context_get_background_color(style, GTK_STATE_FLAG_NORMAL, &color);
     sMozFieldBackground = GDK_RGBA_TO_NS_RGBA(color);
     gtk_style_context_get_color(style, GTK_STATE_FLAG_NORMAL, &color);