vtk + gtk - out of border bug

[z pekar gmail com]

Hi,
2 attached c++ files show implementation of vtk binding to gtk (based
on gtkglext) - I was told that there vtk simply draws into a gtk
widget.
On windows (linux works fine) I get problems with resizing app's
window containing this vtkGtk widget (see attached image - red arrow)
- vtk stuff gets out of its borders. The question is: how does vtk
determines the dimensions of the widget it has to draw to? what can be
done about it?
thank you in advance
Zeev Pekar

http://home.in.tum.de/~pekar/vtkGtkRenderWindowInteractor.h
http://home.in.tum.de/~pekar/vtkGtkRenderWindowInteractor.cpp
http://home.in.tum.de/~pekar/outOfBorderBug.jpg