I have been searching for a Silverlight behavior where you have the ability to resize a column. Normally you can do such a thing with a GridSplitter onto a grid with several columns.
Unfortunately this doesn’t work when you also wants to implement something like a hide and show menu column.
Therefore I created this behavior myself and released it on CodePlex. So if you are developing a Silverlight application and you find yourself in need of a simple behavior that allows you to resize an element by dragging either in height or width, go to the ResizeDragBehavior on Codeplex.
The solution also includes a sample project where you can see how you can easily setup a menupanel-based interface.
The behavior is fully compatible with Expression Blend.