DockPanelSuite is a great open source set of dockable window tools which can make your WinForms apps a sweet suite if you’re not able to use the dockable bits in the 3.0 Framework. (Why am I so limited, you ask? Think support for Windows 2000 clients. Let’s not go there. It hurts.)
I ran into an irritating problem where I shot myself in the foot I mean some idiot missed something which cost me a silly bit of time trying to isolate. The DockContent.HideOnClose property will keep a DockContent form opened, but inactive (hidden) if you have it set true. This can cause some serious head scratching if you’re trying to figure out why this one form out of four isn’t closing, disposing its resources, and going away to the closed form graveyard somewhere east of the middle of nowhere. (That would likely be close to El Nido, California, population 32 when I lived there decades ago.)
DockContent.HideOnClose. Don’t miss it.