xcb: fix drag and drop when window is hidden

This patch fixes drag and drop operation on XCB platform when window
will be hidden. The window can be hidden during dnd operation by
switching virtual desktops or by minimizing all windows (show desktop)
using key shortcut.

The ShapedPixmapWindow must grab mouse before dnd operation if mouse is
not grabbed by other window (like in Qt4).

Task-number: QTBUG-46243
Change-Id: I807bc842719a2d0ea0f4dcb733c06c1fd08813e1
Reviewed-by: Shawn Rutledge <shawn.rutledge@theqtcompany.com>

1 files changed, 3 insertions, 0 deletions

diff --git a/src/plugins/platforms/xcb/qxcbconnection.h b/src/plugins/platforms/xcb/qxcbconnection.h
index 6d26e88fa2..a6a7b9e7ca 100644
--- a/src/plugins/platforms/xcb/qxcbconnection.h
+++ b/src/plugins/platforms/xcb/qxcbconnection.h
@@ -469,6 +469,8 @@ public:
 
     QXcbWindow *focusWindow() const { return m_focusWindow; }
     void setFocusWindow(QXcbWindow *);
+    QXcbWindow *mouseGrabber() const { return m_mouseGrabber; }
+    void setMouseGrabber(QXcbWindow *);
 
     QByteArray startupId() const { return m_startupId; }
     void setStartupId(const QByteArray &nextId) { m_startupId = nextId; }
@@ -649,6 +651,7 @@ private:
     Qt::MouseButtons m_buttons;
 
     QXcbWindow *m_focusWindow;
+    QXcbWindow *m_mouseGrabber;
 
     xcb_window_t m_clientLeader;
     QByteArray m_startupId;