Windows: Implement automatic mouse capture in QPA.

Qt expects the mouse to be captured on any button press
until release.

Remove flags to store capture, use WinAPI GetCapture() instead.
Remove setMouseGrabEnabled_sys(), streamline code.

Replacement for the reverted change
6b5bbc531b30d8ece25425e39843c6ae1af1d045 for QTBUG-25977.

Task-number: QTBUG-27132
Task-number: QTBUG-27039
Task-number: QTBUG-25977
Task-number: QTBUG-26962
Change-Id: If86428eabfadcafd16da10f134a419f833185272
Reviewed-by: Qt Doc Bot <qt_docbot@qt-project.org>
Reviewed-by: Miikka Heikkinen <miikka.heikkinen@digia.com>
Reviewed-by: Jørgen Lind <jorgen.lind@nokia.com>

1 files changed, 3 insertions, 3 deletions

diff --git a/src/plugins/platforms/windows/qwindowswindow.h b/src/plugins/platforms/windows/qwindowswindow.h
index 35790e2739..2bcca8710f 100644
--- a/src/plugins/platforms/windows/qwindowswindow.h
+++ b/src/plugins/platforms/windows/qwindowswindow.h
@@ -126,7 +126,8 @@ public:
         SizeGripOperation = 0x100,
         FrameStrutEventsEnabled = 0x200,
         SynchronousGeometryChangeEvent = 0x400,
-        WithinSetStyle = 0x800
+        WithinSetStyle = 0x800,
+        AutoMouseCapture = 0x1000 //! Automatic mouse capture on button press.
     };
 
     struct WindowData
@@ -179,6 +180,7 @@ public:
 
     virtual bool setKeyboardGrabEnabled(bool grab);
     virtual bool setMouseGrabEnabled(bool grab);
+    inline bool hasMouseCapture() const { return GetCapture() == m_data.hwnd; }
 
     virtual bool startSystemResize(const QPoint &pos, Qt::Corner corner);
 
@@ -249,7 +251,6 @@ private:
     inline bool isFullScreen_sys() const;
     inline void setWindowState_sys(Qt::WindowState newState);
     inline void setParent_sys(const QPlatformWindow *parent) const;
-    inline void setMouseGrabEnabled_sys(bool grab);
     void destroyWindow();
     void registerDropSite();
     void unregisterDropSite();
@@ -261,7 +262,6 @@ private:
     HDC m_hdc;
     Qt::WindowState m_windowState;
     qreal m_opacity;
-    bool m_mouseGrab;
     QWindowsWindowCursor m_cursor;
     QWindowsOleDropTarget *m_dropTarget;
     unsigned m_savedStyle;