"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.'
Re: "Type Error: ToolbarControl.getSettingByType is not a function box keeps appearing!
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.