Fix for TextCtrl problem as reported by Vegh

Move definition of wxMenuItem to /gtk/menuitem.h
  Radical change of how to insert a child into a
    paren window. As C++ doesn't have any VMT in
    a class's consructor, I have to use a callback.
  Fixed culumn resizing bug in wxListCtrl
  Fixed menu height bug in MDI code


git-svn-id: https://svn.wxwidgets.org/svn/wx/wxWidgets/trunk@955 c3d73ce0-8a6f-49c7-b76d-6d57e0e08775

src/generic/listctrl.cpp

@@ -674,6 +674,7 @@ wxListHeaderWindow::wxListHeaderWindow( wxWindow *win, wxWindowID id, wxListMain
 //  m_currentCursor = wxSTANDARD_CURSOR;
   m_currentCursor = (wxCursor *) NULL;
   m_resizeCursor = new wxCursor( wxCURSOR_SIZEWE );
+  m_isDraging = FALSE;
 }
 
 void wxListHeaderWindow::DoDrawRect( wxPaintDC *dc, int x, int y, int w, int h )