Diagram in a grid, postioning when sizing grid

I have a diagram in a grid, the grid uses (Enhanced) GridSplitter to allow resizing. Resizing the grid manually using the splitter causes the diagram to automatically reposition to the center. However part of the enhancement of the splitter is collapse/expand buttons, which basically just have a StoryBoard on the ColumnDefinition of the grid. But when the storyboard is finished after expanding and the diagram comes into view again, it is positioned at a wrong location. While expanding you see the tree coming into view, but when the expanding is finished it moves partly (70%) out of view again. Just a slight manual resize moves it in the correct position.

Is there something that I can do on the storyboard finished or so to get it positioned correctly?

Added the Stretch=“Uniform” to the diagram. It now resizes with the sizing of the grid, but it became worse when expanding using the storyboard, when the expand is finished the tree becomes as small as possible and still partly out of view.

You’re using Silverlight, right? Are you targeting Silverlight 4? If so, are you using GoSilverlight version or (beta)? (beta) Silverlight 3

Here’s how GoXam DLLs are numbered:
m.n.b.3 is compiled for Silverlight 3 (or WPF 3.5).
m.n.b.4 is compiled for Silverlight 4 (or WPF 4).

Is this an extension of the GridSplitter that you defined?
If you change it not to animate the change, do the Diagram contents size/position themselves the way you want?