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wm_activate - why is hwndPrevious null?

Posted on 2000-02-17
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Last Modified: 2013-12-03
hey..
i need to get the handle of the window that is taking focus from my window... wm_activate is what i should use but hwndPrevious is always null..
docs say that 'This handle can be NULL' which doesnt tell me a whole lot :)
what do i do to get the hwnd?
thanks
-vickio
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Question by:Vickio
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Expert Comment

by:JMu
ID: 2533930
This is a quess. It's null, when window of an another process is acticated and not null when window of the same process is activated.

You could try GetActiveWindow in WM_ACTIVATE.

JMu
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Author Comment

by:Vickio
ID: 2534154
hmm, yeah your right, the window being activated must be of the same process....
calling GetActiveWindow doesnt work though cause WM_ACTIVATE is called before the window loses focus...

anyone else have an idea on how i can do this? if not i'll give JMu the points.

-vickio
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JMu earned 350 total points
ID: 2534215
Oops, GetActiveWindow() is thread specific function. If calling thread does not have active window, it returns NULL.

Looks like you have to call GetForegroundWindow() in WM_ACTIVATE.

Does this work?

JMu
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Author Comment

by:Vickio
ID: 2534239
cool, GetForegroundWindow works perfect :)
thanks
-vickio
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Expert Comment

by:DarrinE
ID: 2534256
GetFocus() maybe of assistance - the return value is the handle to the window with the keyboard focus. If the calling thread's message queue does not have an associated window with the keyboard focus, the return value is NULL.

Even if GetFocus returns NULL, another thread's queue may be associated with a window that has the keyboard focus.

Use the GetForegroundWindow function to retrieve the handle to the window with which the user is currently working. You can associate your thread's message queue with the windows owned by another thread by using the AttachThreadInput function.

Let me know how you go

DarrinE
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