ebp and exitting a thread

[V Coder]

My program launches a thread (in the WM_CREATE) handler.

When this thread exits naturally, if it changes the value of ebp before exitting, then the program terminates, without apparently processing WM_CLOSE or WM_DESTROY. If on the other hand the thread ends with ebp intact, the program waits for closure (click the x) and exits with WM_CLOSE and WM_DESTROY.

Why does this happen please?

Also, does exitting a thread automatically give any signal to the main program? Or does one need to send the message in another way? Thanks.

[Petroizki]

You must follow the basic rules of register usage in Windows. You can change eax, ecx and edx, but any other register you use, must be preserved.