Fix scrolling bug where client size was reported wrong

when the scrollbar size was not subtracted when
    using a targetwindow != this.


git-svn-id: https://svn.wxwidgets.org/svn/wx/wxWidgets/trunk@41291 c3d73ce0-8a6f-49c7-b76d-6d57e0e08775

src/gtk/scrolwin.cpp

@@ -118,7 +118,8 @@ void wxScrollHelperNative::AdjustScrollbars()
     int w, h;
     int vw, vh;
 
-    m_targetWindow->m_hasScrolling = m_xScrollPixelsPerLine != 0 || m_yScrollPixelsPerLine != 0;
+    // this flag indicates which window has the scrollbars
+    m_win->m_hasScrolling = m_xScrollPixelsPerLine != 0 || m_yScrollPixelsPerLine != 0;
 
     m_targetWindow->GetVirtualSize( &vw, &vh );