Windows QPA: Fix handling of override cursors

Override cursors were not restored when nested or in a dual
monitor setups.

The default cursor stored in QWindowsCursor::m_overriddenCursor
was clobbered by subsequent calls to QWindowsCursor::setOverrideCursor().
This caused for example the wait cursor to remain active when
switching to Help Mode in Qt Creator. Add a check preventing that.

Make the variable static so that it is shared between the cursors
of multiple screens.

Amends b05d1c2ebfebf0f427a92668c0a7b177d0952012.

Task-number: QTBUG-65001
Change-Id: Iead5804d317f73dedd78d22c1c85c62b5349ab83
Reviewed-by: Oliver Wolff <oliver.wolff@qt.io>

1 files changed, 5 insertions, 1 deletions

diff --git a/src/plugins/platforms/windows/qwindowscursor.cpp b/src/plugins/platforms/windows/qwindowscursor.cpp
index e7ba08b719..1da7de7451 100644
--- a/src/plugins/platforms/windows/qwindowscursor.cpp
+++ b/src/plugins/platforms/windows/qwindowscursor.cpp
@@ -548,6 +548,8 @@ CursorHandlePtr QWindowsCursor::standardWindowCursor(Qt::CursorShape shape)
     return it != m_standardCursorCache.end() ? it.value() : CursorHandlePtr(new CursorHandle);
 }
 
+HCURSOR QWindowsCursor::m_overriddenCursor = nullptr;
+
 /*!
     \brief Return cached pixmap cursor or create new one.
 */
@@ -623,7 +625,9 @@ void QWindowsCursor::setOverrideCursor(const QCursor &cursor)
 {
     const CursorHandlePtr wcursor = cursorHandle(cursor);
     if (wcursor->handle()) {
-        m_overriddenCursor = SetCursor(wcursor->handle());
+        const HCURSOR previousCursor = SetCursor(wcursor->handle());
+        if (m_overriddenCursor == nullptr)
+            m_overriddenCursor = previousCursor;
     } else {
         qWarning("%s: Unable to obtain system cursor for %d",
                  __FUNCTION__, cursor.shape());