Ability to shrink and expand a rectangle around its center

**Is your feature request related to a problem? Please describe.**

I'm building a data set for object detection. I'm using ML to give me initial predictions for bounding boxes. These predictions tend to have good centers, but the size of the box needs to be refined. As I want to keep the center, it would be great if I could shrink and expand a rectangle symmetrically around the center.

**Describe the solution you'd like**
Perhaps when dragging one of the handles on a rectangle, the opposing handle would move in the opposite direction. This would let me shrink width/height separately (using the top/bot/left/right handles), or both at the same time (using the corner handles).

**Describe alternatives you've considered**
I have to manually do both sides, but this risks the center moving