Needed: A popup window without a taskbar icon

I am designing a UI engine that needs to render into popup (WS_POPUP) windows. As these windows cannot be children of other windows, each instance is given its own taskbar icon.

I need a way to prevent the taskbar icons from appearing for certain windows that are created as "dialogs". I cannot use an OS-provided dialog because they all have frames (and I can't figure out how to render into them) or a tool-created custom dialog (which seem to require the CLR).

I am not an expert with the windows API and I feel that I have missed something obvious...

Also: Anything involving CLI/CLR is not an开发者_如何学编程 option.

EDIT:

The WS_EX_NOACTIVATE style can be used for this purpose as well, though the activation behavior would need to be emulated by the program.

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If you set the WS_EX_TOOLWINDOW extended style for your window, it won't be shown in the task bar or Alt+Tab list. This does cause the window to be rendered slightly differently, however (thinking floating tool palette).