JavaFX is relying on an undocumented distributed notification (AppleColorPreferencesChangedNotification) to catch changes to the accent color. In macOS 26 Tahoe this notification isn't sent. Based on my testing it looks like we should be registering for the documented NSSystemColorsDidChangeNotification on the default notification center instead.

Note that in Tahoe this color is labeled the Theme Color in the Appearance pane.

I suppose we should also be using NSView.viewDidChangeEffectiveAppearance instead of AppleInterfaceThemeChangedNotification but as of now that undocumented notification is still working.

This can be tested using Monkey Tester > Tools > Platform preferences monitor.