I set them to be radio buttons rather than checkboxes and game them each the same 'name' attribute (to put them in a radio group), and a 'value' attribute (which, judging from options.js, you don't have to use). You can now only select one of them at a time.
I also noticed the helper text labels had the editable-text cursor over them instead of the expected default cursor, so I added a line to the body{} section of the CSS to make sure it's always the default unless overridden by another class.
I set them to be radio buttons rather than checkboxes and game them each the same 'name' attribute (to put them in a radio group), and a 'value' attribute (which, judging from options.js, you don't have to use). You can now only select one of them at a time.
I also noticed the helper text labels had the editable-text cursor over them instead of the expected default cursor, so I added a line to the body{} section of the CSS to make sure it's always the default unless overridden by another class.
Hope that helps!