Changing function key shortcuts (e.g., swapping F2 and F9 back to what they used to be) should also reorder the button row at the bottom. The expected behavior is really to have the function keys F2 to F10 listed in order, and if one of them is unassigned, the button should be blank (which is how the console applications using this type of UI, e.g., Midnight Commander, handle unassigned function keys).