Move buttons in Manage Assignments window do not update at ends

[Chris Uglow]

INFO
- Windows 10 Home 21H2
- Homebank 5.6
- GTK+ 3.24.33

WHERE
Manage Assignments

WHAT
Select the first or last assignment in the list and click the active move button (down if first item or up if last item) OR click "move to...", type a number within the existing range and click move.

HOW
The inactive move button remains inactive even when the item is no longer at the start or end of the list. It only becomes active when a different list item is selected and then the previously moved item is reselected. I would expect the move button to become active as soon as it becomes a valid action.

(Note the opposite is also true: the move button does not become inactive when moving an item from the middle to the beginning or end of the list, but this does not seem to cause any issues other than being slightly inconsistent)

RELATED
There is a similar bug "Moving assignment rule is not subject to saving and moving to position>99 fails" that also concerns moving items in the Manage Assignments window but it does not cover this bug.