Bugzilla

**Affected versions**
* 76.0.1, 77.0b7, 78.0a1 (2020-05-20);

**Affected platforms**
* Windows 10, macOS 10.15.4, Ubuntu 18.04;

**Steps to reproduce**
1. Launch Firefox with a fresh profile, and access https://edition.cnn.com/
2. Click on the ETP shield;
3. Hover over the  [Site not working?]  string;
4. On the same [row] move the mouse to the right;

**Expected result**
* hover effect over the  [Site not working?]  string in effect only while mouse cursor is over the string;

**Actual result**
* hover effect applied over  [Site not working?]  while holding mouse on the row;

**Regression range**
* First bad: 2019-07-18
* Last good: 2019-07-17
* Pushlog: [URL}(https://hg.mozilla.org/mozilla-central/pushloghtml?fromchange=b6d154b2309846531934289c1e167208fc385ac3&tochange=bc0fdcef296f2d429e3f4b5f29e264ffc185163d)
* not a regression, visible with redesign of panel;

**Additional notes**
* attached recording with the issue.

**Affected versions**
* 76.0.1, 77.0b7, 78.0a1 (2020-05-20);

**Affected platforms**
* Windows 10, macOS 10.15.4, Ubuntu 18.04;

**Steps to reproduce**
1. Launch Firefox with a fresh profile, and access https://edition.cnn.com/
2. Click on the ETP shield;
3. Hover over the  [Site not working?]  string;
4. On the same [row] move the mouse to the right;

**Expected result**
* hover effect over the  [Site not working?]  string in effect only while mouse cursor is over the string;

**Actual result**
* hover effect applied over  [Site not working?]  while holding mouse on the row;

**Regression range**
* First bad: 2019-07-18
* Last good: 2019-07-17
* Pushlog: [URL](https://hg.mozilla.org/mozilla-central/pushloghtml?fromchange=b6d154b2309846531934289c1e167208fc385ac3&tochange=bc0fdcef296f2d429e3f4b5f29e264ffc185163d)
* not a regression, visible with redesign of panel;

**Additional notes**
* attached recording with the issue.