I'm afraid I cannot fully understand your exact question/scenario. Could you please elaborate a bit more on your requirements. What do you mean by enable the RadTreeList? Do you want to enable/disable some controls into the RadTreeList?
Regarding your second question:
You could get the client side dataitems objects and call set_selected(bool) function which will selected the RadTreeList row. For more information please check out the following online documentation articles:
Please give it try and let me know if you experience any problems. Looking forward for your reply.
the Telerik team
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