Fix a rare race condition when showing windows

When setting a window to translucent shortly before showing it with the
OpenGL graphics system, the hijacking would call XDestroyWindow without
resetting the internal state. This might lead to the window waiting for
a map notify message forever.

The patch now properly resets the internal state when destroying the old
window, so it'll get mapped correctly when show() is called.

Reviewed-by: Denis Dzyubenko

1 files changed, 10 insertions, 1 deletions

diff --git a/src/gui/kernel/qwidget_x11.cpp b/src/gui/kernel/qwidget_x11.cpp
index 9085e98..ff6f215 100644
--- a/src/gui/kernel/qwidget_x11.cpp
+++ b/src/gui/kernel/qwidget_x11.cpp
@@ -905,8 +905,17 @@ void QWidgetPrivate::create_sys(WId window, bool initializeWindow, bool destroyO
             inputContext->setFocusWidget(q);
     }
 
-    if (destroyw)
+    if (destroyw) {
         qt_XDestroyWindow(q, dpy, destroyw);
+        if (QTLWExtra *topData = maybeTopData()) {
+#ifndef QT_NO_XSYNC
+            if (topData->syncUpdateCounter)
+                XSyncDestroyCounter(dpy, topData->syncUpdateCounter);
+#endif
+            // we destroyed our old window - reset the top-level state
+            createTLSysExtra();
+        }
+    }
 
     // newly created windows are positioned at the window system's
     // (0,0) position. If the parent uses wrect mapping to expand the