remove wxWindow::Clear() from wxDFB and wxMGL which was unused (probably replaced by ClearBackground()) and conflicted with methods with the same name in other classes

git-svn-id: https://svn.wxwidgets.org/svn/wx/wxWidgets/trunk@49202 c3d73ce0-8a6f-49c7-b76d-6d57e0e08775

src/mgl/window.cpp

@@ -1099,14 +1099,6 @@ void wxWindowMGL::GetTextExtent(const wxString& string,
 // painting
 // ---------------------------------------------------------------------------
 
-void wxWindowMGL::Clear()
-{
-    wxClientDC dc((wxWindow *)this);
-    wxBrush brush(GetBackgroundColour(), wxSOLID);
-    dc.SetBackground(brush);
-    dc.Clear();
-}
-
 void wxWindowMGL::Refresh(bool eraseBack, const wxRect *rect)
 {
     if ( m_eraseBackground == -1 )