Bugzilla

### Beta/Release Uplift Approval Request
* **User impact if declined**: Windows users who use the overflow panel heavily (with many widgets in there, including extensions). Clearly not the vast majority of users but the UI looks bad when that happens.
* **Is this code covered by automated tests?**: No
* **Has the fix been verified in Nightly?**: Yes
* **Needs manual test from QE?**: No
* **If yes, steps to reproduce**: 
* **List of other uplifts needed**: None
* **Risk to taking this patch**: Low
* **Why is the change risky/not risky? (and alternatives if risky)**: This is not risky because it is a trivial CSS change on the overflow panel and we made sure to only fix the UI bug and defer clean-ups in follow-up patches.
* **String changes made/needed**: 
* **Is Android affected?**: No

### Beta/Release Uplift Approval Request
* **User impact if declined**: Windows users who use the overflow panel heavily (with many widgets in there, including extensions). Clearly not the vast majority of users but the UI looks bad when that happens.
* **Is this code covered by automated tests?**: No
* **Has the fix been verified in Nightly?**: Yes
* **Needs manual test from QE?**: No
* **If yes, steps to reproduce**: 
* **List of other uplifts needed**: None
* **Risk to taking this patch**: Low
* **Why is the change risky/not risky? (and alternatives if risky)**: This is *not* risky because it is a trivial CSS change on the overflow panel and we made sure to only fix the UI bug and defer clean-ups in follow-up patches.
* **String changes made/needed**: 
* **Is Android affected?**: No

PS: when grafting this patch, can you please fix up the author name (`unknown` => `William Durand`)? (assuming that's possible) Thanks!