New answers tagged selection
0
You could replace the radio buttons by check boxes as well. This would give your users the desired ability and enable them to select more than one class. If finally no users were selected, then the Post button should be inactive.
2
If they can only select one, I would go with a treeview type control, primarily because this allows you to display the top-level options, that they must select and not overload the user with sub-options they can't select, once the user has made their top-level select, I would then show those to the user.
For example:
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