Allow overriding of X error functions

app/x11_util.h

Index: app/x11_util.h
diff --git a/app/x11_util.h b/app/x11_util.h
index 8ebed23ccdca63e550412f44c1f08b43b33546ff..c07f42c08f501098d36660f5bf8023597ddc7030 100644
--- a/app/x11_util.h
+++ b/app/x11_util.h
@@ -173,8 +173,10 @@ void GrabWindowSnapshot(GtkWindow* gdk_window,
 // Change desktop for |window| to the desktop of |destination| window.
 bool ChangeWindowDesktop(XID window, XID destination);
 
-// Sets the X Error Handlers so we can catch X errors and crash.
-void SetX11ErrorHandlers();
+// Enable the default X error handlers. These will log the error and abort
+// the process if called. Use SetX11ErrorHandlers() from x11_util_internal.h
+// to set your own error handlers.
+void SetDefaultX11ErrorHandlers();
 
 }  // namespace x11_util