1. Launch Firefox.
2. Try to open a new window from the context menu on the icon in Dock
## Actual Result
- Firefox is not responsible with rainbow cursor.
- Firefox does not comeback and I need to quit Firefox forcely.
- I reproduce this bug a few days ago.
- I does not face this bug rarely on a new profile
## Environment
- macOS Big Sur 11.0.1 /hg.mozilla. org/mozilla- central/ rev/b0865ea5846 21ce9e7f6883356 5e3d8ae117ce32
- I reproduced this bug on macOS Caralina 10.15.7 too.
- https:/
## Steps to reproduce
1. Launch Firefox.
2. Try to open a new window from the context menu on the icon in Dock
## Actual Result
- Firefox is not responsible with rainbow cursor.
- Firefox does not comeback and I need to quit Firefox forcely.
- I reproduce this bug a few days ago.
- I does not face this bug rarely on a new profile