Please refer to the attached sample project.
Hello, David,
Please excuse me for the delayed reply.
Currently, this issue is not planned for our next official release. Please make sure that you cast your vote for it in order to increase its priority. The more votes an item gathers, the higher its priority becomes. You can also subscribe for status changes by clicking the Follow button. Thus, you will get notified once the status of this item is updated.
Please excuse us for the inconvenience caused.
We will do our best to address this problem accordingly.
Regards,
Dess | Tech Support Engineer, Sr.
Progress Telerik
Would love to see this issue fixed. It's occurs with any Office app add-in. I've tested in Word, Excel, Outlook, and MS Project. It occurs in all of them and affects both RadDropDownList and RadCheckedDropDownList. A link to my workaround is below, but a proper fix would be great:
https://www.telerik.com/forums/dropdownlist-mousewheel-behavior-in-c-outlook-vsto-add-in#bPyjtaCFZ0Sxm7wZ4SnX0g