Fixed bug 4085 - X11: Allow configuring _NET_WM_BYPASS_COMPOSITOR through SDL hints

Callum McGing

This patch allows the user to disable the behaviour that blocks the compositor through a new hint: SDL_VIDEO_X11_NET_WM_BYPASS_COMPOSITOR. This allows tools or other windowed applications to behave properly under KWin.

include/SDL_hints.h

@@ -211,6 +211,18 @@ extern "C" {
  */
 #define SDL_HINT_VIDEO_X11_NET_WM_PING      "SDL_VIDEO_X11_NET_WM_PING"
 
+/**
+ * \brief A variable controlling whether the X11 _NET_WM_BYPASS_COMPOSITOR hint should be used.
+ * 
+ * This variable can be set to the following values:
+ * "0" - Disable _NET_WM_BYPASS_COMPOSITOR
+ * "1" - Enable _NET_WM_BYPASS_COMPOSITOR
+ * 
+ * By default SDL will use _NET_WM_BYPASS_COMPOSITOR
+ * 
+ */
+#define SDL_HINT_VIDEO_X11_NET_WM_BYPASS_COMPOSITOR "SDL_VIDEO_X11_NET_WM_BYPASS_COMPOSITOR"
+
 /**
  *  \brief  A variable controlling whether the window frame and title bar are interactive when the cursor is hidden 
  *

src/video/x11/SDL_x11window.c

@@ -579,11 +579,12 @@ X11_CreateWindow(_THIS, SDL_Window * window)
     wintype = X11_XInternAtom(display, wintype_name, False);
     X11_XChangeProperty(display, w, _NET_WM_WINDOW_TYPE, XA_ATOM, 32,
                     PropModeReplace, (unsigned char *)&wintype, 1);
-
-    _NET_WM_BYPASS_COMPOSITOR = X11_XInternAtom(display, "_NET_WM_BYPASS_COMPOSITOR", False);
-    X11_XChangeProperty(display, w, _NET_WM_BYPASS_COMPOSITOR, XA_CARDINAL, 32,
-                    PropModeReplace,
-                    (unsigned char *)&compositor, 1);
+    if (SDL_GetHintBoolean(SDL_HINT_VIDEO_X11_NET_WM_BYPASS_COMPOSITOR, SDL_TRUE)) {
+        _NET_WM_BYPASS_COMPOSITOR = X11_XInternAtom(display, "_NET_WM_BYPASS_COMPOSITOR", False);
+        X11_XChangeProperty(display, w, _NET_WM_BYPASS_COMPOSITOR, XA_CARDINAL, 32,
+                        PropModeReplace,
+                        (unsigned char *)&compositor, 1);
+    }
 
     {
         Atom protocols[3];