Focus_set() (Focus() is the same thing) is probably what you need (w.focus() gives widget w focus when its window is clicked). Grab_set() takes ALL the events for the application, which usually makes it real hard to do anything outside the grabbing widget.

Focus_force() will give the widget and its window focus without having to click the window. You probably want to be a little thoughtful about doing this, as it's easy to be rude.

Also, lift() will bring your window to the top, if that's a problem.

I wish I had a good reference for this topic, but I don't. Try it out.