Toolbar sample code on Polyscope 3.x CB-series

Hi,
By definition the UR+ toolbar is not available on CB-series Polyscope 3.x, but has anyone implemented a similar function and can share a sample code here?
I think it should be technically possible to create a very small JFrame with ‘always on top’ behaviour and add mouse listerers that react to user actions.
Are there any restrictions on using such technique other than the safety checksum must remain always visible?
Thanks,
Csaba