Problem programmatically selecting tabs remotely

Does anyone know how to correctly programmatically select a tab in a tab control? The twist is that I want to do it from another process.

I've been through MSDN and written the code to send the NOTIFY (TCN_SELCHANGING) message, then the TCM_SETCURSEL message, then finally the NOTIFY (TCN_SELCHANGE) message. The funny thing is that the tab does change, but the client area (new dialog box) never gets loaded. So the tab changes but the rest of the control doesn't.

My guess is the final message, which is the message on which the client area processing relies, either doesn't get processed correctly, or has been written incorrectly by the programmer...

This final message requires a pointer to a structure, but because it's not in the same process as the tab control maybe it is not copied correctly with the message to the control?

Any help would be appreciated. Thanks.