Thanks for looking into it.
You don't need to write code. Just test the "Examples C#" window you provide with the Nevron toolkit, like I wrote ("C:\Program Files (x86)\Nevron Software\Nevron .NET Vision 2011.1 for VS2010\Examples\UI\WinForm\CSharp\bin\Release\Nevron.Examples.UI.WinForm.exe"). This comes with the toolkit install. I've not changed it.
It shows the same problem. It starts out maximized when you launch it and is using the VistaPlus frame. Just restore it, minimize it, restore it, minimize it, etc.. You'll notice after each restore that the bottom grows by a few pixels if you are using a frame or a skin. When you select Edit>Frame>System Default it stops doing that. My program has the same exact problem.