TextBox expanding with surrounding Grid but not with text

Question

A window has a Grid with two columns. The left column contains a control with a constant width but with a height that adapts. The right column contains a TextBox that takes up a

Answer 1

Have you tried setting the MaxWidth property on just the TextBox?

Edit after OP's comment

I would try getting rid of the ScrollViewer. The sizing used in the Grid's layout should take care of re-sizing and the scroll bar settings on the TextBox should take care of the rest.