borderPainted property

[PGriffith]

Yeah. The Look and Feel has a fairly opinionated way things should be painted.

There's some more context on the bug here:

Upgrade version makes buttons dissapear (possible bug?)

Okay, let’s make sure I have things correct. By my count, there’s three problems you’re describing in this thread. Upon upgrade, some of your buttons disappear outright. I think I understand what’s gone wrong. There’s an issue in the LaF with the borderPainted property (causing the button to become invisible) so we removed the property entirely. However, older windows could still have a change from the default value serialized, so you end up with your issue - invisible buttons. We’ll see if…

That thread also has a potential workaround; changing the Synthetica.background.alpha property changes the rendering process for buttons, which might get you closer to the style you want with borderPainted disabled.