[FULL-SCREEN] INPUT.MOUSEPOSITION OUTPUT DOES NOT MATCH THE DISPLAYED VIEW ON THE SCREEN

To reproduce the bug follow the steps
1. Unarchive "ButtonBug" project
2. Open "ButtonBug" project
3. Add "SamepleScene" scene to Scenes in Builds in BuildSettings
4. Build & Run in MacOs platform
5. Click the upper right corner ui button
6. Change to full screen mode

Expect Result :
Unity 2019.3.15f1(non full screen mode):
The button can successfully clicked and make the app change to full screen mode , the input.mousePosition will returns correct coordinates.

Unity 2019.3.15f1(full screen mode with black boarders):
The button can't successfully clicked . Input.mousePosition will return values that are out of the screen coordinates. User used workaround to get correct position of the mouse.