Hello Francois,
This has not been requested by our customers and thus it was not done. I have created an item in the PITS for this improvement and it accumulates enough votes we will consider its implementation, because it is a change in the behavior of the control that will affect all users. This is the URL where you can vote, comment and monitor the idea:
http://www.telerik.com/support/pits.aspx#/public/aspnet-ajax/12852.
All the best,
Marin Bratanov
the Telerik team
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