When using the "Details" button to hide/unhide the available options under "History -> Clear Recent History", you'll end up with a large void area in the UI which extends the entire modal dialog box. I figured there was a bug already created for this but I couldn't find anything when searching "Clear History". STR (example: https://youtu.be/FCOggyB4clU): * launch fx * select "History -> Clear Recent History" * hide the selectable options by clicking on the "^ Details" button * you'll notice an empty area where the selectable options used to be * unhide the selectable options by clicking on the "\/ Details" button You'll notice that there's now a huge empty area in the UI as shown in the screenshot example.

Mass wontfix for bugs affecting firefox 52.

For how much it may look strange, the Clear Recent History dialog is not part of the history component... Actually there's no good component for it.