Hello Svein Thomas,
Thank you for contacting us.
You can achieve this by subscribing to the MouseDoubleClick event of RadCalendar and handle it as it is demonstrated below:
sender, MouseEventArgs e)
CalendarCellElement cell = (
Should you have any further questions, feel free to ask.
the Telerik team
Q2’11 SP1 of RadControls for WinForms is available for download (see what's new); also available is the Q3'11 Roadmap for Telerik Windows Forms controls.