[Solved] Why doesn’t my Windows API callback function run? [closed]

Question

The documentation for SendMessageCallback tells you, why your callback will not ever be called:

If the target window belongs to a different thread from the caller, then the callback function is called only when the thread that called SendMessageCallback also calls GetMessage, PeekMessage, or WaitMessage.

The target window obviously belongs to a different thread, because it runs in a different process. Your code doesn’t perform any message retrieval. No callback.

Accepted Answer

The documentation for SendMessageCallback tells you, why your callback will not ever be called:

If the target window belongs to a different thread from the caller, then the callback function is called only when the thread that called SendMessageCallback also calls GetMessage, PeekMessage, or WaitMessage.

The target window obviously belongs to a different thread, because it runs in a different process. Your code doesn’t perform any message retrieval. No callback.