Fix EditorPropertyResource focus outline being drawn behind the preview

(cherry picked from commit 0b47f1be8c94a4a037980d7d3f1f79559c09ce58)

editor/editor_properties.cpp

@@ -2922,6 +2922,8 @@ EditorPropertyResource::EditorPropertyResource() {
 	preview->set_margin(MARGIN_TOP, 1);
 	preview->set_margin(MARGIN_BOTTOM, -1);
 	preview->set_margin(MARGIN_RIGHT, -1);
+	// This is required to draw the focus outline in front of the preview, rather than behind.
+	preview->set_draw_behind_parent(true);
 	assign->add_child(preview);
 	assign->connect("gui_input", this, "_button_input");