Hello.

DoubleAnimation crashes in XAMLPad (May CTP) when animating Width or Height without specifying both "From" and "To" values, or when a base value isn't set. This is because the animation infers these values from the base value, which may not be available until layout execution. Setting the Width or Height on the element or in a style usually resolves the issue. However, I encountered a case where animating a MenuItem's width failed even after attempting to set a default width through a style. A suggested solution involved explicitly setting the width on the element, as the animation infers the 'To' value from the base value, which needs to be available for a smooth transition. I then tried setting a default Width on the MenuItem Style and the crash still occurs in XAMLPad. My next step is to test this in a WinFX application.