Widget's input value

A string or any object that can be converted to a string. If the string starts with "+" or "-" character, the group box displays its title using a checkbox in place of an ordinary label. If the checkbox is checked, the group box's children are enabled; otherwise they are disabled and inaccessible. The value can also be a boolean which controls the checked state of the group box.

Widget's output value

The checked state of the group box.