From daed7200b33f710853e8d2f0792c3ede596754ef Mon Sep 17 00:00:00 2001
From: Ben Harris <bjh21@bjh21.me.uk>
Date: Sat, 19 Apr 2025 09:13:06 +0100
Subject: [PATCH] GTK: create backing Cairo surface of similar type to window

Specifically, this creates the surface using
gdk_window_create_similar_surface() where that's available.
---
 unix/window.c | 6 ++++++
 1 file changed, 6 insertions(+)

diff --git a/unix/window.c b/unix/window.c
index 1379b6ef..bbaaa854 100644
--- a/unix/window.c
+++ b/unix/window.c
@@ -819,8 +819,14 @@ static void drawing_area_setup(GtkFrontend *inst, int width, int height)
         inst->surface = NULL;
     }
 
+#if GTK_CHECK_VERSION(2,22,0)
+    inst->surface = gdk_window_create_similar_surface(
+        gtk_widget_get_window(inst->area),
+        CAIRO_CONTENT_COLOR, inst->backing_w, inst->backing_h);
+#else
     inst->surface = cairo_image_surface_create(
         CAIRO_FORMAT_ARGB32, inst->backing_w, inst->backing_h);
+#endif
 #endif
 
     draw_backing_rect(inst);