In order to put all the items in edit mode you can add their indexes to the EditIndexes collection of the RadTreeList and then rebind the control:
sender, EventArgs e)
Another option would be if you use only TemplateColumns that have textboxes in their ItemTemplates so that they look like they are in edit mode and will allow input when the TreeList is in display mode. More information on the different columns in RadTreeList can be found here
You can enable the recursive selection of the RadTreeList by setting the AllowRecursiveSelection
property to true. More information on the specifics of this feature can be found here
and a live demo is available here
(you can enable the recursive selection from the configuration panel in the demo). Note that this feature requires an implicit postback to rebind the control so its better to use ajax or the pop up that holds the TreeList might automatically close when the page is reloaded.
the Telerik team