I've been a .NET developer for several years now and this is still one of those things I don't know how to do properly. It's easy to hide a window from the taskbar via a property in both Windows Forms and WPF, but as far as I can tell, this doesn't guarantee (or necessarily even affect) it being hidden from the Alt-Tab dialog. I've seen invisible windows show up in Alt-Tab, and I'm just wondering what is the best way to guarantee a window will never appear (visible or not) in the Alt-Tab dialog.
Update: Please see my posted solution below. I'm not allowed to mark my own answers as the solution, but so far it's the only one that works.
Update 2: There's now a proper solution by Franci Penov that looks pretty good, but haven't tried it out myself. Involves some Win32, but avoids the lame creation of off-screen windows.
