To reproduce:

1. Open the attached project (Overcharge Strip.zip)
2. Open the Test scene
3. Try opening Fullscreen Mode, Resolution, Anti-aliasing dropdowns
4. Observe that they do not behave the way they should
5. Delete the Canvas and Graphics Raycaster components from the GameController -> Canvas_UI -> Window_Options_Top game object

Expected: the dropdowns should not be opening above the initial dropdown position and should close when clicked outside the dropdown when they are children of the object with a Canvas, which in turn is a child of another object with a Canvas

Reproduced in 2018.2.0f2, 2018.2.2f1, 2018.3.0a7
Could not test in earlier version because the UI objects in question are in the prefab, but the prefab breaks in earlier versions and I am not able to reproduce the issue by recreating the prefab and its structure