Hello Marcus Lambert,
As of Q3 MouseUp/MouseDown events are handled by RadGridView and for the time being the only way to listen for those events is to subscribe using code. For example:
sender, Telerik.Windows.Input.MouseButtonEventArgs args)
Depending on your scenario it is not mandatory to subscribe for mouse events on all rows or cells. Subscribing for those events of RadGridView only might do the job. Could you please provide more information about your scenario so that we could try to provide an acceptable solution.
We have just recently introduced the AddMouseDownHandler with three argument where the last one allows you to handle already handled events. The new method is available in our latest internal build.
We are also evaluating several ideas on how we can improve the current situation with event handling and we will try to provide better experience as soon as possible
the Telerik team