From 9fdc0f08ce69ae0a41f75b10067c29492472f6a6 Mon Sep 17 00:00:00 2001
From: Po Lu <luangruo@yahoo.com>
Date: Fri, 11 Feb 2022 13:44:42 +0800
Subject: [PATCH] Set _NET_WM_OPAQUE_REGION on non-GTK3 toolkits when using 32
 bit visual

* src/xfns.c (x_set_alpha_background): Set opaque region if
opaque.

* src/xterm.c (x_update_opaque_region): New parameter
`configure'.  All callers changed.
(handle_one_xevent): Call `x_update_opaque_region' on configure
events.
---
 src/xfns.c  | 13 +++++++++++++
 src/xterm.c | 32 ++++++++++++++++++++++++++++----
 2 files changed, 41 insertions(+), 4 deletions(-)

diff --git a/src/xfns.c b/src/xfns.c
index 7d91f32ad4a..849fa72f39f 100644
--- a/src/xfns.c
+++ b/src/xfns.c
@@ -730,6 +730,11 @@ x_set_wait_for_wm (struct frame *f, Lisp_Object new_value, Lisp_Object old_value
 static void
 x_set_alpha_background (struct frame *f, Lisp_Object arg, Lisp_Object oldval)
 {
+#ifndef HAVE_GTK3
+  unsigned long opaque_region[] = {0, 0, FRAME_PIXEL_WIDTH (f),
+				   FRAME_PIXEL_HEIGHT (f)};
+#endif
+
   gui_set_alpha_background (f, arg, oldval);
 
 #ifdef USE_GTK
@@ -749,6 +754,14 @@ x_set_alpha_background (struct frame *f, Lisp_Object arg, Lisp_Object oldval)
 		       XA_CARDINAL, 32, PropModeReplace,
 		       NULL, 0);
     }
+#ifndef HAVE_GTK3
+  else
+    XChangeProperty (FRAME_X_DISPLAY (f),
+		     FRAME_X_WINDOW (f),
+		     FRAME_DISPLAY_INFO (f)->Xatom_net_wm_opaque_region,
+		     XA_CARDINAL, 32, PropModeReplace,
+		     (unsigned char *) &opaque_region, 4);
+#endif
 }
 
 static void
diff --git a/src/xterm.c b/src/xterm.c
index 66666229cd9..e7736f741a0 100644
--- a/src/xterm.c
+++ b/src/xterm.c
@@ -345,7 +345,7 @@ static void x_wm_set_icon_pixmap (struct frame *, ptrdiff_t);
 static void x_initialize (void);
 
 static bool x_get_current_wm_state (struct frame *, Window, int *, bool *);
-static void x_update_opaque_region (struct frame *);
+static void x_update_opaque_region (struct frame *, XEvent *);
 
 /* Flush display of frame F.  */
 
@@ -366,7 +366,6 @@ x_flush (struct frame *f)
 static void
 x_drop_xrender_surfaces (struct frame *f)
 {
-  x_update_opaque_region (f);
   font_drop_xrender_surfaces (f);
 
 #ifdef HAVE_XRENDER
@@ -440,14 +439,37 @@ record_event (char *locus, int type)
 #endif
 
 static void
-x_update_opaque_region (struct frame *f)
+x_update_opaque_region (struct frame *f, XEvent *configure)
 {
+#ifndef HAVE_GTK3
+  unsigned long opaque_region[] = {0, 0,
+				   (configure
+				    ? configure->xconfigure.width
+				    : FRAME_PIXEL_WIDTH (f)),
+				   (configure
+				    ? configure->xconfigure.height
+				    : FRAME_PIXEL_HEIGHT (f))};
+#endif
+
+  if (!FRAME_DISPLAY_INFO (f)->alpha_bits)
+    return;
+
+  block_input ();
   if (f->alpha_background < 1.0)
     XChangeProperty (FRAME_X_DISPLAY (f),
 		     FRAME_X_WINDOW (f),
 		     FRAME_DISPLAY_INFO (f)->Xatom_net_wm_opaque_region,
 		     XA_CARDINAL, 32, PropModeReplace,
 		     NULL, 0);
+#ifndef HAVE_GTK3
+  else
+    XChangeProperty (FRAME_X_DISPLAY (f),
+		     FRAME_X_WINDOW (f),
+		     FRAME_DISPLAY_INFO (f)->Xatom_net_wm_opaque_region,
+		     XA_CARDINAL, 32, PropModeReplace,
+		     (unsigned char *) &opaque_region, 4);
+#endif
+  unblock_input ();
 }
 
 
@@ -9712,7 +9734,7 @@ handle_one_xevent (struct x_display_info *dpyinfo,
 	      f->output_data.x->has_been_visible = true;
 	    }
 
-	  x_update_opaque_region (f);
+	  x_update_opaque_region (f, NULL);
 
           if (not_hidden && iconified)
             {
@@ -10350,6 +10372,7 @@ handle_one_xevent (struct x_display_info *dpyinfo,
 	x_cr_update_surface_desired_size (any,
 					  configureEvent.xconfigure.width,
 					  configureEvent.xconfigure.height);
+      x_update_opaque_region (f, &configureEvent);
 #endif
 #ifdef USE_GTK
       if (!f
@@ -10378,6 +10401,7 @@ handle_one_xevent (struct x_display_info *dpyinfo,
 	  x_cr_update_surface_desired_size (f, configureEvent.xconfigure.width,
 					    configureEvent.xconfigure.height);
 #endif
+	  x_update_opaque_region (f, &configureEvent);
           f = 0;
 	}
 #endif
-- 
2.39.5