aui docking works well on systems with solid window dragging turned off

git-svn-id: https://svn.wxwidgets.org/svn/wx/wxWidgets/trunk@42843 c3d73ce0-8a6f-49c7-b76d-6d57e0e08775

include/wx/aui/floatpane.h

@@ -57,6 +57,7 @@ private:
     static bool isMouseDown();
 private:
     wxWindow* m_pane_window;    // pane window being managed
+    bool m_solid_drag;          // true if system uses solid window drag
     bool m_moving;
     wxRect m_last_rect;
     wxRect m_last2_rect;