There are controls that handle MouseLeftButtonDown (like Button control). That is why it is not working by default. For this case we have added AttachOnHandledEvents
property. Just set it to True and you will be
able to open the context menu on MouseLeftButtonDown event.
Let us know if you need more information.
the Telerik team
Do you want to have your say when we set our development plans? Do you want to know when a feature you care about is added or when a bug fixed? Explore the Telerik Public Issue Tracking
system and vote to affect the priority of the items