[gtksourceview] css: avoid drawing background on "textview text" selector

[Christian Hergert <chergert src gnome org>]

commit a2aee5aee857c93642df91cd2670f6797c6212a7
Author: Christian Hergert <chergert redhat com>
Date:   Fri Feb 11 15:35:11 2022 -0800

    css: avoid drawing background on "textview text" selector
    
    This can cause extra large drawing to occur in situations that we can
    avoid. There are still others we need to improve on, but this is
    definitely a start.

 gtksourceview/GtkSourceView.css | 5 +++++
 gtksourceview/gtksourceview.c   | 2 ++
 2 files changed, 7 insertions(+)
---
diff --git a/gtksourceview/GtkSourceView.css b/gtksourceview/GtkSourceView.css
index e049364c..f0094e93 100644
--- a/gtksourceview/GtkSourceView.css
+++ b/gtksourceview/GtkSourceView.css
@@ -167,6 +167,11 @@ GtkSourceStyleSchemePreview.selected image {
   margin: 6px;
 }
 
+/* Ensure we don't double draw backgrounds */
+textview.GtkSourceView text {
+  background: transparent;
+}
+
 textview.GtkSourceMap {
   font-size: 1.75pt;
   line-height: 4px;
diff --git a/gtksourceview/gtksourceview.c b/gtksourceview/gtksourceview.c
index ed55e1ef..4789a016 100644
--- a/gtksourceview/gtksourceview.c
+++ b/gtksourceview/gtksourceview.c
@@ -1410,6 +1410,8 @@ gtk_source_view_init (GtkSourceView *view)
        GtkEventController *key;
        GtkDropTarget *dest;
 
+       gtk_widget_add_css_class (GTK_WIDGET (view), "GtkSourceView");
+
        priv->tab_width = DEFAULT_TAB_WIDTH;
        priv->tabs_set = FALSE;
        priv->indent_width = -1;