The item from "Manage snoozed tabs" panel remains fixed and doesn't have any hover effect if previously long clicking it

[SoftVision-CarmenFat]

[Affected versions]:

• Firefox 58.0.2 and above
• Snooze Tabs 1.1.0

[Affected Platforms]:

• All Windows
• All Mac
• All Linux

[Prerequisites]:

• Have a Firefox profile with the latest Snooze Tabs add-on version (https://github.com/bwinton/SnoozeTabs/releases/tag/1.1.0) loaded as a temporary add-on.
• Have at least one item in the "Manage snoozed tabs" panel.

[Steps to reproduce]:

1. Open the browser with the profile from prerequisites and open a new tab.
2. Click the "Snooze Tabs" button from the toolbar.
3. Long click one of the snoozed items.
4. Move the mouse cursor away from the item and let go of the click.
5. Hover the item from step 3 and observe what happens next.

[Expected result]:

• The item slides a few pixels to the left.
• The page favicon is no longer visible.
• "Delete" button is displayed on the right side of the item.

[Actual results]:

• The item remains fixed so that the page favicon is still displayed and the "Delete" is not shown.

[Notes]:

• This is not reproducible with the Test Pilot version of Snooze Tabs.
• The snoozing options are also selected if long clicking them.
• Attached a screencast of the issue: