Bug 1654323 - Use GtkTextView.text.selection to get selection colors in GTK. r=stransky

Differential Revision: https://phabricator.services.mozilla.com/D84814

widget/gtk/WidgetStyleCache.cpp

@@ -1073,6 +1073,9 @@ static GtkStyleContext* GetCssNodeStyleInternal(WidgetNodeType aNodeType) {
       style = CreateSubStyleWithClass(MOZ_GTK_SCROLLED_WINDOW,
                                       GTK_STYLE_CLASS_FRAME);
       break;
+    case MOZ_GTK_TEXT_VIEW_TEXT_SELECTION:
+      style = CreateChildCSSNode("selection", MOZ_GTK_TEXT_VIEW_TEXT);
+      break;
     case MOZ_GTK_TEXT_VIEW_TEXT:
     case MOZ_GTK_RESIZER:
       style = CreateChildCSSNode("text", MOZ_GTK_TEXT_VIEW);

widget/gtk/gtkdrawing.h

@@ -211,6 +211,8 @@ typedef enum {
   MOZ_GTK_TEXT_VIEW,
   /* The "text" window or node of a GtkTextView */
   MOZ_GTK_TEXT_VIEW_TEXT,
+  /* The "selection" node of a GtkTextView.text */
+  MOZ_GTK_TEXT_VIEW_TEXT_SELECTION,
   /* Paints a GtkOptionMenu. */
   MOZ_GTK_DROPDOWN,
   /* Paints a dropdown arrow (a GtkButton containing a down GtkArrow). */

widget/gtk/nsLookAndFeel.cpp

@@ -1130,6 +1130,7 @@ void nsLookAndFeel::EnsureInit() {
   mFieldText = GDK_RGBA_TO_NS_RGBA(color);
 
   // Selected text and background
+  style = GetStyleContext(MOZ_GTK_TEXT_VIEW_TEXT_SELECTION);
   gtk_style_context_get_background_color(
       style,
       static_cast<GtkStateFlags>(GTK_STATE_FLAG_FOCUSED |