in Premiere CC, how do you create a TALL rectangular mask? I can create a rectangular mask in Premiere CC, and I can resize it. But how do I change just one dimension (make it more narrow) while keeping the corners at right angles? Dragging a corner point manually probably won't maintain a 90-degree corner.
Finally figured it out (with some help). You can drag a whole side at a time! Here's how:


Click one of the 2 corners to (subtly) select it.
Shift-click-and-drag the other corner.


That will select the whole side between the two corners. It will also limit your "dragging path" to paths that are at 45 degrees or 90 degrees relative to the corner's original position. That enables you to keep your rectangle rectangular.