macOS: window background flashes when switching tabs after waking up the display

Discussed in Discord help channel: https://discord.com/channels/1005603569187160125/1545858093244743681

Reproduce steps:

1. Connect Mac with an external monitor and close the laptop lid
2. Open Ghostty with 3+ tabs, and switch them
3. Disconnect the display
4. Reconnect the display
5. Switch the tabs and see how the background turns transparent which causing the flash

Minimal config:

background-opacity = 0.95
background-blur = true