"Type Error: ToolbarControl.getSettingByType is not a function box keeps appearing!
A box keeps popping up with the above error. Trying to click out of it brings up another window with the same message, this time with a box one can check stating 'Prevent this page from creating additional dialogs.'
This issue can be caused by an extension that isn't working properly.
Start Firefox in Safe Mode to check if one of the extensions (Firefox/Tools > Add-ons > Extensions) or if hardware acceleration is causing the problem (switch to the DEFAULT theme: Firefox/Tools > Add-ons > Appearance).
- Do not click the Reset button on the Safe mode start window or otherwise make changes.