I believe there is an issue when the dhtmlx scheduler and tree are “used” at the same time.
I found this doing testing related to upgrading from dhtmlx suite 4.0.3 to 4.1.2
Dynamic loading and opening items dynamically work properly in 4.0.3 I get the following error in 4.1.2:
Uncaught TypeError: undefined is not a function
dhtmlXTreeObject._loadDynXML
dhtmlXTreeObject._HideShow
dhtmlXTreeObject.onRowClick
Column 625206 at .url of this snippet in dhtmlx.js
else{this.loadXML(c+dhtmlx.url(c)+“uid=”+a+“&id=”+this._escape(e))}
V4.0.3. has getUrlSymbol(src) instead of url(c)
I confirmed the issue by adding the bolded line in your example:
dhtmlxSuite_v412_pro\samples\dhtmlxTree\12_loading_processing_data\03_pro_dyn_operations.html