Thank you for contacting us.
Unfortunately, I am not able to reproduce the issue. I have tested the scenario with the latest three versions of RadControls for Winforms and it seems that the popup is there and it opens the editor. Would you please let me know which version you are currently using? Also, please make sure that you have an installation of our controls, which will put the assemblies in the necessary places. Further, please share any details concerning your machine and the RadControls for WinForms installations that you have.
I am looking forward to your reply.
the Telerik team