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
The answer is based on Leom's answer.
The solution works great when you enlarge the window, but the resizing is not smooth when you make the window smaller. As the textbox participates in the grid's layout, it has to perform layout process multiple times. You can fix that by putting the texbox in the canvas, so the change of the size of the textbox no longer triggers the grid's re-layout.
The updated code: