By default the ContextMenu should be displayed exactly at the mouse position, but you could have set properties that changed their behavior, hence the undesired effect. Could you send us the XAML of your context menu? If you are using additional code for the menu (except ItemClick event handler or commands) a sample application would be of great help resolving the issue.
the Telerik team
Explore the entire Telerik portfolio by downloading the Ultimate Collection trial package. Get it now >>