Hi Frank Chou,
Thank you for the writing.
I tested the described scenario using our latest release - Q2 2011 SP1 and I could not observe an issue. Please could you send us a sample application and a detailed description on how to reproduce it. Just a suggestion, you could close manually the drop down popup by calling the CloseDropDown
method when CTRL-S is pressed.
I will be glad to help further and I am looking forward to your reply.
All the best,
the Telerik team
Q1’11 SP1 of RadControls for WinForms is available for download
; also available is the Q2'11 Roadmap
for Telerik Windows Forms controls.