Dependency arrows explain themselves and stay out of the way

You can draw a dependency arrow from one task card to another on the canvas, so the second card waits until the first is done. The first time you draw one, a short note next to the pointer now says what the arrow will do. An arrow that runs across a third card no longer gets in the way: you can still open and move that card from anywhere on it, and the arrow's remove button moves to a spot no card covers.