Integrating with Scheduler lightbox

The dhtmlxScheduler_editors library allows comboboxes as lighbox controls.
Is there a way to integrate a combobox with checkboxes?

If it can only be done via a custom lighbox control, what should be the code?

Unfortunately the only solution is to create your own custom editor for the dhtmlxSheduler similar to the simple combo editor.
Here you can find a source code for the dhtmlxCombo integration: … editors.js