The "Keep sidebar open" button has a small delay when hovering the sidebar

[SoftVision-CarmenFat]

[Affected versions]:

• Firefox 51.0.1 and above
• Tab Center 1.29.0

[Affected Platforms]:

• All Windows
• All Mac OS
• All Linux

[Prerequisites]:

• The "xpinstall.signatures.required" is set to "false" and latest Tab Center add-on is installed on a new clean profile.

[Steps to reproduce]:

1. Open the browser with the profile from prerequisites;
2. Click on the "Shrink sidebar when not in use" button from top of the sidebar;
3. Hover the mouse outside the sidebar;
4. Hover again over the sidebar and observe the top part of it.

[Expected result]:

• All items from the top of the sidebar are displayed instantly.

[Actual result]:

• The "Keep sidebar open" button has a slight delay.

[Notes]:

• Please see the screen recording of the issue:

[ericawright]

yes, this is in the works to being fixed thanks to @fvsch