Clicking on a vector sprite in the sprite pane changes how far offscreen it can move

[adroitwhiz]

Expected Behavior

Clicking on a sprite in the sprite pane should not affect its fencing behavior.

Actual Behavior

When you click on a sprite in the sprite pane, its precise bounds are calculated from its convex hull as part of the blue selection box effect, and for vector sprites, the fence bounds switch over from the AABB bounds to the precise ones. Scratch 2.0 always uses the AABB bounds, even for vector sprites.

Steps to Reproduce

In this project:

1. Press space to move the sprite as far to the right as it will go
2. Click "Sprite1" in the sprite pane, so that the blue selection box flashes above it
3. Press space again and notice how the position of the sprite changes