[Collab] Modified scene message box is hidden under Collab toolbar

To reproduce:
1. Create a new project
2. Create scene
3. Push project to Collab
4. Modify scene (DO NOT SAVE) + modify another asset (so that there are publishable changes)
5. Push changes

Expected vs Actual: modified scene message box should not hide under Collab toolbar

Reproduced: 5.5.3f1, 5.5.6f1, 5.6.5p1, 2017.1.3f1, 2017.2.1p3, 2017.3.1p1, 2018.1.0b7, 2018.2.0a1