The "Price Wise" door hanger can wrongly be zoomed in and out

[SoftVision-CarmenFat]

[Affected versions]:

• Firefox Release v63.0 and up

[Affected Platforms]:

• All Windows
• All Mac OS
• All Linux

[Prerequisites]:

• Have a Firefox profile with the latest version of the "Price Wise" add-on (8.0.0) downloaded from (download link).

[Steps to reproduce]:

1. Open the browser with the profile from prerequisites.
2. Click the "Price Wise" button from the toolbar.
3. Press "Ctrl" and while turning up the mouse wheel, observe the Price Wise panel.

[Expected result]:

• Nothing happens, the panel cannot be zoomed in/out.

[Actual result]:

• The panel is wrongly zoomed in.

[Notes]:

• The issue is also happening while zooming out.
• The panel is stuck if zooming out at maximum value, so the user has to close the panel and click again the Price Wise toolbar button in order to trigger the panel again;
• The issue is not reproducible using the zoom shortcut keys ("Ctrl"&"+/-").
• Here is a screen recording of the issue: