Just try to include these files after dhtmlx.js in the library now - to test. And write to the support system - we’ll try to fix your issue in dhtmlx.js file.
I addede dhtmlxcalendar.js and nothing changed, then I added also the dhtmlxform_item_calendar.js and the calendar stop to work (it’s neither shown) due to the error:
this.doAttachChangeLS is not a function
waiting for a solution, in the meantime I’m going to write a formatter.
You need to add all js files form this archive in usual order (form + foem_item_calendar + calendar)…
The best way - write to support system and attach your dhtmlx.js file to fix it.