How to send a mouse click event to a hidden window?

Question

Recognising that a bit of interop may be required, how do I send a mouse click event to a window that is currently not being displayed? I have an application that is running

Answer 1

Use Spy++ to find out what Windows messages are sent to the window when it's shown and you physically click it with the mouse, and then use SendMessage to send those messages directly.

Answer 2

If you can get the HWND of the window, it's pretty easy. Use PostMessage() with WM_LBUTTONDOWN for a left click.

Example: click on position 10,10 (untested, C)

HWND hWnd = (hwnd of window)
WORD mouseX = 10;
WORD mouseY = 10;
PostMessage(hWnd,WM_LBUTTONDOWN,0,MAKELPARAM(mouseX,mouseY));