currently in the React Dialog, you cannot have a Dialog with a Title but without a Close (X) button visible... Whereas in the KendoUI Dialog for jQuery, you can with the 'closable' configuration property... this should also be dynamic to hide/show/enable/disable the close (X) button while the Dialog is visible (ie. when an operation is pending, disable the close button or hide it)
The property is available in version 1.3 https://www.telerik.com/kendo-react-ui/components/dialog/api/DialogProps/#toc-closeicon