Open Radar

 
Summary:
When using Screen Sharing, Spaces either doesn’t repaint the screen correctly or behaves erratically because Beam Sync is disabled.

If you create multiple spaces, Mission Control will eventually not be able to draw on screen. If you disable Beam Sync so they can actually draw, you can’t interact with Mission Control.

Beam Sync is disabled because of this Radar: rdar://19382113

Steps to Reproduce:

1. Assign Mission Control to a hotkey (switching spaces using Control-Arrow keys won’t work over Screen Sharing.)

2. Use the hotkey to invoke Mission Control.

3. Use the + button in the upper-right corner of the window to create 10 new spaces.

4. Use the hotkey to invoke Mission Control.

5. Use Quartz Debug to turn off Beam Sync in the Quartz Debug Settings utility window (Command-1)

6. Use the hotkey to invoke Mission Control.

7. Move a Finder window from one space to another space.

Expected Results:

Everything should work.

Actual Results:

In step 4, Mission Control will not be able to repaint the screen.

In step 7, you can’t move a window between spaces.


Regression:

This is new behavior in Yosemite.