Insert/Cut frame floating offset from the canvas

in Bug reports
This bug has been introduced with the new Animation frame managing tool.

Steps to reproduce:
1. Add a new animation
2. make sure it stops at the last tile
3. choose the "animation frame manager tool"
4. hover over the edge.
Expected behavior:
Nothing should happen?
Actual behavior:
The insert/cut frame selection appears but offset from the cursor position.

Steps to reproduce:
1. Add a new animation
2. make sure it stops at the last tile
3. choose the "animation frame manager tool"
4. hover over the edge.
Expected behavior:
Nothing should happen?
Actual behavior:
The insert/cut frame selection appears but offset from the cursor position.