DisplayGLX::isValidNativeWindow, avoid X11 exiting the program

src/libANGLE/renderer/gl/glx/DisplayGLX.cpp

@@ -708,23 +708,16 @@ egl::Error DisplayGLX::restoreLostDevice(const egl::Display *display)
 
 bool DisplayGLX::isValidNativeWindow(EGLNativeWindowType window) const
 {
-    // There is no function in Xlib to check the validity of a Window directly.
-    // However a small number of functions used to obtain window information
-    // return a status code (0 meaning failure) and guarantee that they will
-    // fail if the window doesn't exist (the rational is that these function
-    // are used by window managers). Out of these function we use XQueryTree
-    // as it seems to be the simplest; a drawback is that it will allocate
-    // memory for the list of children, because we use a child window for
-    // WindowSurface.
-    Window root;
-    Window parent;
-    Window *children = nullptr;
-    unsigned nChildren;
-    int status = XQueryTree(mGLX.getDisplay(), window, &root, &parent, &children, &nChildren);
-    if (children)
-    {
-        XFree(children);
-    }
+
+    // Check the validity of the window by calling a getter function on the window that
+    // returns a status code. If the window is bad the call return a status of zero. We
+    // need to set a temporary X11 error handler while doing this because the default
+    // X11 error handler exits the program on any error.
+    auto oldErrorHandler = XSetErrorHandler(IgnoreX11Errors);
+    XWindowAttributes attributes;
+    int status = XGetWindowAttributes(mXDisplay, window, &attributes);
+    XSetErrorHandler(oldErrorHandler);
+
     return status != 0;
 }