How to implement "Open With" command using ShellExecuteEx and wait for it to finish?

Question

Seemingly simple task: I want to open the standard Windows dialog for picking the application to be used for opening the file, and then wait for this application to finish. The internet tells that ShellExecuteEx is the way to go.

Ok, so here's the code:

    SHELLEXECUTEINFO sei;
    ::ZeroMemory(&sei,sizeof(sei));
    sei.cbSize = sizeof(sei);        
    sei.lpFile = L"path/to/document";
    sei.lpVerb = L"openas";
    sei.lpParameters = L"";
    sei.nShow = SW_SHOW;
    sei.fMask = SEE_MASK_NOCLOSEPROCESS | SEE_MASK_INVOKEIDLIST ;
    BOOL ret = ::ShellExecuteEx(&sei);
    DWORD waitResult = ::WaitForSingleObject(sei.hProcess, INFINITE);

But it doesn't work: specifying SEE_MASK_INVOKEIDLIST flag makes hProcess to always be NULL, even if a new process was indeed launched.

How can this be fixed? Thanks in advance!

Answer 1

The shell was never designed to do this and even if it was it would not work 100% of the time because not everything launches a new process (DDE, IShellExecuteHook, IDropTarget, IExecuteCommand etc).

If writing your own dialog is acceptable then you might want to take a look at IEnumAssocHandlers. Raymond Chen recently did a blog post about it.