The current implementation of the MultiSelectTree component doesn't provide the option to define a custom header and footer inside its popup.

Providing the mentioned properties will keep the consistency among the different DropDown components as the discussed options are available in other DropDown components like the:

• DropDownList - https://www.telerik.com/kendo-react-ui/components/dropdowns/dropdownlist/custom-rendering/#toc-headers-and-footers 
• MultiSelect - https://www.telerik.com/kendo-react-ui/components/dropdowns/multiselect/custom-rendering/#toc-headers-and-footers