InSendMessage function (winuser.h)
Determines whether the current window procedure is processing a message that was sent from another thread (in the same process or a different process) by a call to the SendMessage function.
To obtain additional information about how the message was sent, use the InSendMessageEx function.
If the window procedure is processing a message sent to it from another thread using the SendMessage function, the return value is nonzero.
If the window procedure is not processing a message sent to it from another thread using the SendMessage function, the return value is zero.
|Minimum supported client||Windows 2000 Professional [desktop apps only]|
|Minimum supported server||Windows 2000 Server [desktop apps only]|
|Header||winuser.h (include Windows.h)|
|API set||ext-ms-win-ntuser-message-l1-1-0 (introduced in Windows 8)|