Script editor doesn't refresh when in focus

[petebankhead]

Bug report

Describe the bug
The script editor should refresh its contents when in focus when File → Auto refresh files is selected.

The reason is that this makes it easier to edit a script outside QuPath (e.g. in IntelliJ).

Expected behavior
After editing a script file outside QuPath, bringing the script editor into focus should result in the script being refreshed if File → Auto refresh files is selected.

Desktop (please complete the following information):

• OS: All
• QuPath Version: v0.4.1 (and likely v0.4.0)

Additional context
This seems to be a regression introduced amidst the other script editor changes.

Switching to a different script is now needed to trigger the refresh.