C# window height only gets bigger, not smaller

Question

I've got a form with a collapsible group box (got it from http://www.codeproject.com/Articles/12835/XP-Style-Collapsible-GroupBox). I'm using it basically to show/hide advanced options on the form. The group-box itself is not at issue, however, as I did the same thing with just a regular Panel that I changed the Visible property on and the issue is the same:

When I hide this box, I want the window to shrink accordingly. So I've got code when you click on the box header that basically goes like:

if (OptionsPanel.IsCollapsed)
    this.Height -= (OptionsPanel.Height - OptionsPanel.CollapsedHeight);
else
    this.Height += (OptionsPanel.Height - OptionsPanel.CollapsedHeight);

The problem is- when you expand the box, the window does indeed grow accordingly, but when you collapse the box, it doesn't shrink. In fact, nothing I do seems able to make the window smaller - I've even tried hard-coding the window sizes, and it never gets smaller, only bigger.

Is there something I'm missing to make this work? Or is there a better component out there that will do this right? Honestly I'm shocked that there isn't a default control in the Toolbox for doing this sort of thing, as it seems like a fairly common thing to do, and I've seen things like this on a lot of forms. Doesn't seem like the kind of thing you should have to go to 3rd party plugins or roll your own code for.

Answer 1

Did you try adding AutoSizeMode=GrowAndShrink property?

Preferably, both AutoSize=true, AutoSizeMode=GrowAndShrink

In C#

OptionsPanel.AutoSize = true;
OptionsPanel.AutoSizeMode = AutoSizeMode.GrowAndShrink;

Reference: http://msdn.microsoft.com/en-us/library/system.windows.forms.autosizemode.aspx

Answer 2

Make sure your Form's AutoSize is set to True and AutoSizeMode set to GrowAndShrink the default is GrowOnly