Fixes an issue on Windows 11 where clicking in the very corner of the taskbar doesn't open the Start menu on left-aligned taskbars when the start menu button is "in a sticky corner".
Windows 11's taskbar has an InputSite window (Windows.UI.Input.InputSite.WindowClass) that intercepts mouse clicks before they reach the Start button.
This seems to be caused by the "sticky corners" feature, and thus only affects multi-monitor setups.
This mod hooks CreateWindowInBand to detect when the InputSite window is created,
then installs a thread-specific mouse hook on its thread. This hook intercepts mouse
clicks at the corner region and invokes the Start menu via UI Automation when the
real button doesn't handle the click.