I can’t seem to figure this out. I have two group boxes on the left side of my form window. When the window is normal size (1000×700), the two boxes are the same. However, when the window is maximized, it ends up looking like this:

What I want is for both the “Log” group box and the tab control to extend down to the bottom of the window. I have tried messing with anchoring, but that just seems to move it and not resize it. Docking fills the whole side. What options do I have here?
Make Log’s
Make tab control’s