3-state checkboxes can have their initial value set to checked or undetermined -- this adds support for the undetermined state to the handler (only allowed if the style includes wxCHK_3STATE). Closes #22468.
3-state checkboxes can have their initial value set to checked or undetermined -- this adds support for the undetermined state to the handler (only allowed if the style includes wxCHK_3STATE). Closes #22468.