Scrollable notification popup is not restored correctly when cleared.

I am using XFCE 4.18 in Linux Mint 21.2.

If the popup notification history is too long to fit on the monitor it becomes scrollable, so all entries can be viewed by scrolling a mouse wheel.

When the log is subsequently cleared, the notification history is not restored to its default state, and the controls ('Do Not Disturb', 'Clear Log', and 'Notification Settings...') are not visible.

Additionally, the popup no longer responds to mouse wheel scrolling, so it is not apparent how to fix this. Through trial-and-error I have discovered that it can be returned to its default state by using the arrow keys.

I suspect the code does not take into account the possibility that the contents of the notification history popup are greater in size than the height of the monitor.