Explicitly request our window to not be composited.

This does nothing in KWin though (works anyway), and it looks like other
compositors currently do not support this flag anyway. This makes it
however easier for compositors to fix incompatbilities by adding support
for the flag.

main.c

@@ -512,6 +512,24 @@ int main(int argc, char **argv) {
   XChangeProperty(display, background_window, state_atom, XA_ATOM, 32,
                   PropModeReplace, (const unsigned char *)&fullscreen_atom, 1);
 
+  // Bypass compositing, just in case.
+  Atom dont_composite_atom =
+      XInternAtom(display, "_NET_WM_BYPASS_COMPOSITOR", False);
+  long dont_composite = 1;
+  XChangeProperty(display, background_window, dont_composite_atom, XA_CARDINAL,
+                  32, PropModeReplace, (const unsigned char *)&dont_composite,
+                  1);
+#ifdef HAVE_COMPOSITE
+  if (have_composite) {
+    // Also set this property on the Composite Overlay Window, just in case a
+    // compositor were to try compositing it (xcompmgr does, but doesn't know
+    // this property anyway).
+    XChangeProperty(display, composite_window, dont_composite_atom, XA_CARDINAL,
+                    32, PropModeReplace, (const unsigned char *)&dont_composite,
+                    1);
+  }
+#endif
+
   // Initialize XInput so we can get multibyte key events.
   XIM xim = XOpenIM(display, NULL, NULL, NULL);
   if (xim == NULL) {