If you would like to set event handlers for the Click event to the menu items which you have added in the DropDownButtonElement items collection you should follow the following steps:
1. Open the Items property collection editor of the dropdown button and add the necessary menu items (for example radMenuItem1, radMenuItem2 and radMenuItem3)
2. Then close the editor, go to the property grid and select one of the menu items from the drop-down list (for example radMenuItem1).
3. Set up its Click event.
4. Repeat 2 and 3 steps for the rest menu items.
I hope this information helps.