Steps to reproduce:
1. Open attached Unity project "926739-2D-RAT.zip"
2. Open scene "test"
3. Select Platforms1 to see that it has a Composite Collider 2D Component
4. Expand Platforms1 to find the two child Objects
5. Select either of them
7. Press the button next to Edit Collider in Polygon Collider 2D Component to edit it
6. Hover the mouse over where segments of the Polygon Collider 2D gizmo would be

Expected result: the entire gizmo outlining Polygon Collider 2D is visible
Actual result: only the active part of the Polygon Collider 2D gizmo which the mouse is hovering over is visible (see attached screenshot "polygoncollider2dgizmo.png")

Reproducible with: 5.5.1f1, 5.6.0f1, 5.6.2p2, 2017.2.0b2

Fixed in: 2019.3.0a2