well i have my own version of trim and extend commands, i have been created a "mouse clic" action for trim and extend so i don't need execute this commands, ENTER for select all entities, and clic. i just use Shift+right clic or Ctrl+Shift+right clic to trim or extend the object that is exactly under the right clic, the problem is that Shift key is a bit confuse, and lot of times i get the oposite effect.
i'm trying to simulate ArchiCAD feature: Ctrl+clic = trim and Ctr+Shift+clic = extend
i can't create a mouse clic action with ALT+clic and Ctrl+Alt+clic