How do I make submenus appear in the custom menu block?

How do I make an arrow appear to the right of the text?

menu.addPair( name, action, '\u25ba')

doDeclareVariables

There is a project you already know.

Can you make radio buttons in menus act like radio buttons (only one can be true)?

It just acts like a normal menu.

Yes;
Did you seen a menu working as you want in Snap!?

What?