Or how about right-clicking where you want to split and select "Split" from the popup. If you don't select anything then your cursor is set where you clicked and you can edit.
Same for joining - select your three items, right click and select "Join".
That last comment was from me, not Anonymous.
I'm keen for using the alt key instead of the control key to modify the arrow keys. And please stop popping up each line's detail each time the modifier key is pressed. Thank you.