Scanner results missing arrows

[lokiuox]

Describe the bug
The small "arrows" don't show up in the tree in the Scanner result view until you click on the icon

To Reproduce
Steps to reproduce the behavior:

1. Perform a scan using the Scanner
2. The results view will show up, but the arrows in the tree are missing

4. Click on the icon of the first result
5. The arrows appear

Additional context
For some reason, this doesn't happen when I have a custom theme loaded using the BurpCustomizer extension. I suspect it has something to do with some Swing Look and Feel settings or something.

It's also possible that the correct style doesn't get applied until the tab is actually displayed (this happens with other components, too). In that case, we could add something like a FocusListener somewhere that refreshes the tree when it gets focus.