[BUG] TreeView merged node overlap #991

Description

When the tree view creates transition views with multiple parents, nothing is checking to make sure they are not being drawn to the same place as another transition view. In some cases, this will result in views being drawn on top of one another, making the below tree elements inaccessible

Steps to Reproduce

1. Open a Nurikabe puzzle
2. Create 2 branches from the root tree node with the add node button
3. From each branch, use the Black or White case rule on the same puzzle element
4. If the top and bottom nodes from each case rule transition match and are not mirrored, undo and apply the case rule again
5. Merge the matching nodes from each branch
6. Observe that the merged nodes have been placed on top of each other

Expected Behavior

The tree view should place lay these out such that they do not overlap.

Screenshots

Puzzle Files

No response

Additional Context

Will be fixed in the upcoming ScrollView rewrite.