How to find a input box handle from another application

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C++

MFC

Hello all,

I am developing a simple input method, the requirement is: when some input box in other application, then my input application should show out and after input hide by itself.

Now i set a timer to detect when i should show my window out, so i need to detect the input box window handle of other application, if it is a valid handle, then i will show my input method out. But unfortunately, i don't know to do. Do anybody can help me? thanks very much.

i tried GetForegroundInfo to get the foreground window handle and the focus window handle, but it always return valid value whatever it need input or not.