BUG: Custom trait input not working

@RaresVlaiduc mmm I'd expect it to work also with an HTML string... I have to check it

Then, in createInput() you should return an Element. So instead of returning a simple string, do this:

const el = document.createElement('div');
el.innerHTML = `<input type='checkbox'/>`
return el;

If you want to have a simple checkbox with label, no need to create custom trait, you can just use directly:

editor.DomComponents.addType('text', {
            model: {
              defaults: {
                traits: [
                  {type: 'checkbox', label: 'Fix position when scrolling', name: 'position-sticky'}
                ]
              }
            },
});