Crash when opening full screen child viewport

[kpouer]

Describe the bug

On a Mac full screen windows are opened in a new desktop.
Because of that the parent window is not visible anymore and it causes a crash.
Also when you reduce the parent view the child view disappear as well.

To Reproduce

Example 1

1. Run the example "multiple_viewports" from egui
2. Click deferred or immediate, it happens for both.
3. Reduce the parent window
4. Both window disappear

example 2 full screen on MacOS crash

1. Modify the example "multiple_viewports" from egui to open in full screen
2. Run it
3. Click deferred or immediate, it happens for both.
4. Reduce the parent window
5. Strange behavior of desktops being created then crash

Expected behavior
Should not crash or hide child window

Additional context
This is a regression appeared in that commit (not painting when window is hidden) 1b8a9fe

[kpouer]

I tried to provide a solution in that PR #8226