Stepping inside the drag and drop process (or any other system call)

I have an application that does not use the standard libraries. Instead, it uses stubs to call LoadLibrary/GetProcAddress, then calls functions via the re开发者_Go百科sultant function pointers.

Using the above method my application is calling DoDragDrop in ole32.dll. The call is returning E_UNEXPECTED, which apparently means 'catastophic failure'.

What I want to ask is does anyone know of a way to discover what is happening inside the call to DoDragDrop? Specifically, can I discover what function or variable it is looking for but cannot find? (I am guessing that it wants access to some function or variable that is not loaded at the point I call DoDragDrop, and if I can explicitly load it the call will succeed.) Obviously I can't step into the call - attempting to just runs the function and steps to the line in my code following the DoDragDrop call.

:)

(I'm using VS2005 in XP.)

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I recall having something like this occur when I had forgotten to call OleInitialize(Ex) / CoInitialize(Ex) for the thread making the call. Note the apartment must be STA.