In native GTK apps, if you roll the mouse over a checkbox that has focus, both the
text and the focus box (dashed lines around the text) change color (see attached
screenshot checkbox-rollover-native.png). But under Swing's GTK L&F, the focus box
does not change color (remains black; see attached checkbox-rollover-java.png).
This may also apply to other widget types such as radio buttons, but I didn't have
a chance to verify that.