[Beta9.1] Developing my own widget (extends \IPS\Widget implements \IPS\Widget\Builder) - "Pop-up" menu does not work correctly

Hello,

Developing my own widget (extends \IPS\Widget implements \IPS\Widget\Builder) - there is an ACP option to select the "menu style" as either "Pop-up menu" or "modal".

"Modal" works fine 😉

"Pop-up menu" has (at least) two issues:

1. Advanced=>Custom CSS: does not work. You can edit the CSS (latest Firefox) and put whatever you want. When you click save no errors are reported but the Custom CSS is just silently "lost" - it has no effect and when you go back into the settings all your input has vanished from the "Custom CSS" box. Other settings (e.g. "Box border" are saved as you would expect.
    
2. Pop-up menu is basically a mess:
   1. Too narrow
   2. Fields for both 'Settings' and 'Advanced' tab appear on the same popup as soon as you open the editor to change the settings
   3. Click the 'Visibility' tab and it show the fields for both Visibility and Advanced

Thanks.

John