The popup is too small to be useful after pinning it to the overflow menu in Firefox.
In Firefox I can pin extensions to the overflow menu. That way, they don't take up space when I don't need them to. When I click the KeePassXC icon while it's in the overflow menu I expect it to behave exactly like it would when it isn't pinned to the overflow menu. Observe the normal behaviour in the following screenshot.

After pinning KeePassXC-Browser to the overflow menu, the popup is much narrower than before, as shown in the screenshot below. As a result, the "Connect" button is now invisible and cannot be pressed. Horizontal scrolling (that is, scrolling while holding Shfit) or dragging my text selection to the right both don't seem to work.

The best solution would be to make the popup the same size before and after pinning it to the overflow menu. However, an alternative would be to prevent the overflow of elements to make sure elements are never hidden, but this has the drawback that the popup may become too tall. Maybe both should be done.
KeePassXC - 2.5.1
KeePassXC-Browser - 1.5.4
Operating system: Windows 10
Browser: Firefox 71.0
Seems like this is a Firefox bug: https://bugzilla.mozilla.org/show_bug.cgi?id=1373490
Removing min-width should help...
https://github.com/keepassxreboot/keepassxc-browser/blob/b08966c6fd709e334962e661e43b40ce1345ddfe/keepassxc-browser/popups/popup.css#L8
https://github.com/keepassxreboot/keepassxc-browser/blob/b08966c6fd709e334962e661e43b40ce1345ddfe/keepassxc-browser/popups/popup.css#L14

looks fixed in nightly
