Add class attribute to selected text

[richardhulbert]

I am trying to write a module that allows a user to add any arbitrary class (string) to any selected tag. I am happy to write it but the documentation is can't to say the least.

Whilst there is a module example in the main documentation. This doesn't really explain how to create a button that invokes a dialogue that interacts with selected text. Maybe I haven't found it but there seems to be very little in the way of documentation for Modules.