Funny this. I created project from VS template and tested it a bit. If you shrink the window to a minimum then left and right dockable panes will also shrink and will not grow back. Then I tried the same thing with Visual Studio itself and the same thing happens. Dockable panes shrink, but do not grow back. But at least we have middle area that takes all the non-fixed space. If those dockable panes could be prevented from undocking, hiding, auto-hiding, and if they could be made without titlebars, so that they resemble another client area, then I would have something close to original idea. But without the panes growing back when there's available space.

Mihajlo Cvetanovic wrote: I would like the user to be able to resize controls within dialog That's a tall order. If your actions inspire others to dream more, learn more, do more and become more, you are a leader." - John Quincy Adams You must accept one of two basic premises: Either we are alone in the universe, or we are not alone in the universe. And either way, the implications are staggering” - Wernher von Braun