Function GetFocusedCtrlThread

source/keyboard_mouse.cpp:3728–3755

DWORD GetFocusedCtrlThread(HWND *apControl, HWND aWindow)
{
	// Determine the thread for which we want the keyboard layout.
	// When no foreground window, the script's own layout seems like the safest default.
	DWORD thread_id = 0;
	if (aWindow)
	{
		// Get thread of aWindow (which should be the foreground window).
		thread_id = GetWindowThreadProcessId(aWindow, NULL);
		// Get focus.  Benchmarks showed this additional step added only 6% to the time,
		// and the total was only around 4µs per iteration anyway (on a Core i5-4460).
		// It is necessary for UWP apps such as Microsoft Edge, and any others where
		// the top-level window belongs to a different thread than the focused control.
		GUITHREADINFO thread_info;
		thread_info.cbSize = sizeof(thread_info);
		if (GetGUIThreadInfo(thread_id, &thread_info))
		{
			if (thread_info.hwndFocus)
			{
				// Use the focused control's thread.
				thread_id = GetWindowThreadProcessId(thread_info.hwndFocus, NULL);
				if (apControl)
					*apControl = thread_info.hwndFocus;
			}
		}
	}
	return thread_id;
}