Windows: fix crash on closing an app when native file dialog is opened

The crash was provoked by QThread::terminate() called
for QWindowsDialogThread from QWindowsDialogHelperBase destructor.
It's still not clear why terminating the thread here causes a crash,
but normally we should avoid terminating a thread anyway.

Current changes make several improvements to avoid terminating the
thread. The main problem was that QWindowsDialogThread::run() was never
returned. That's because QWindowsNativeFileDialogBase::close() was not
called on QWindowsDialogHelperBase destruction. The second problem
was that QWindowsNativeFileDialogBase::close() may still not close
native file dialog because it was not able to find HWND for IFileDialog
instance in some circumstances, so make this by more robust way.

Fixes: QTBUG-93298
Pick-to: 6.3
Change-Id: I55c8cf664ae2cf7c41c8cce43a6bb88a2680bf14
Reviewed-by: Friedemann Kleint <Friedemann.Kleint@qt.io>
Reviewed-by: Oliver Wolff <oliver.wolff@qt.io>

1 files changed, 1 insertions, 1 deletions

diff --git a/src/plugins/platforms/windows/qwindowsdialoghelpers.h b/src/plugins/platforms/windows/qwindowsdialoghelpers.h
index de272289c0..64f40bc3a9 100644
--- a/src/plugins/platforms/windows/qwindowsdialoghelpers.h
+++ b/src/plugins/platforms/windows/qwindowsdialoghelpers.h
@@ -31,7 +31,7 @@ class QWindowsDialogHelperBase : public BaseClass
     Q_DISABLE_COPY_MOVE(QWindowsDialogHelperBase)
 public:
     using QWindowsNativeDialogBasePtr = QSharedPointer<QWindowsNativeDialogBase>;
-    ~QWindowsDialogHelperBase() { cleanupThread(); }
+    ~QWindowsDialogHelperBase();
 
     void exec() override;
     bool show(Qt::WindowFlags windowFlags,