Alignment issues when using firefox overflow menu

[IFoundAnotherUsername]

When opening Code Injector using the Overflow Menu, some of the buttons (in the Add Rule window at least) will be wrapped to the next line because they don't fit in the slim window.
This makes it impossible to access them (see image), which is especially annoying because the "Save" button is the first to be wrapped.

My current workaround is not using the overflow menu and putting them in the always visible area (second image; note the missing addon title now it is outside the overflow menu).