Windows Forms controls (as well as many classes in the .NET Framework Class Library (FCL) encapsulate native APIs. You need to research and understand the Windows APIs and common controls to do what you want. For instance, read the Windows Controls[^] and Windowing[^] sections in the Platform SDK. You need to understand window handles, styles, and message pumps. You might try searching CodeProject for existing managed samples (in C#, VB.NET, whatever - it all gets compiled to roughly the same thing), but you'll most likely find the majority of samples in VC++ or MFC. Writing custom menu bars and toolbars in VC++ or MFC is very common and there are plenty of samples both here on CodeProject and on sites like CodeGuru[^]. For example, you'll want to override the protected CreateParams property in your control derivative and use the WS_POPUP (0x80000000) window style. See the Platform SDK for more details about that, which should give you some idea of where to start.
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