Dependencies: pywin32, pyhook

I have a weird 3 screen setup at work (don't ask me why): ...a docked laptop with a 27" monitor to its right and a 19" monitor above the 27" monitor.

I hate having to move the mouse from window to window when switching between windows using Alt-Tab, specially when the mouse has to be moved from the 1st screen to the 3rd screen.

So... I created this simple script to move the mouse to the middle of the new window if Alt-Tab is being used.

Usage:

$ python  mouse_to_active_win.py  True

The parameter (True or False) enables/disables debug prints.

How it works

Setting the mouse position: We'll use the Windows SetCursorPos API to set the mouse position. PyWin32 provides bindings for Win32 API functions, so we just have to make the API call i.e.

# Set cursor position to (100, 100)
win32api.SetCursorPos((100, 100))

Getting the active (foreground) window: GetForegroundWindow returns a handle to the currently active window. The GetWindowText and GetWindowRect APIs can be used to get the window title and dimensions, respectively.

Keyboard hook for Alt-Tab: This is where PyHook comes in; it wraps low-level mouse and keyboard hooks in the Windows Hooking API for use in Python applications.

# Create the hook manager
hm = pyHook.HookManager()

# Register keyboard callback
hm.KeyUp = on_keyboard_event()

pythoncom.PumpMessages()

# Hook into keyboard events
hm.HookKeyBoard()

# The callback...
def on_keyboard_event(event):
    # Check for the Alt-Tab key combination (basically we check for the Tab key event with Alt held down)
    if event.Key == 'Tab' and event.Alt != 0
        # Handle key event
        pass

    # Exit if SIGINT was received
    if sigint_rcvd:
        pass

    return True

Putting it all together: The function that sets the mouse position, set_mouse_position, is run in its own thread.

thread = threading.Thread(target = set_mouse_position, args = (debug, ))
thread.start()

The set_mouse_position function is more or less straight forward save for one minor peculiarity: we need to make sure that the "Task Switching" window has closed before we position the mouse:

# Wait for the 'Task Switching' window to close
while(GetWindowText(GetForegroundWindow()).split('-')[-1] == 'Task Switching'):
    pass
time.sleep(0.25)   # --> Slight delay before continuing...

The rest of the implementation is self-explanatory, on_keyboard_event posts a switch event on Alt-Tab and a quit event on SIGINT (Ctrl-C). A signal handler is installed for handling SIGINT (Ctrl-C).

If you don't want to download or clone the whole repository, you can view the complete source for this script on GitHub here or download the file here