I believe I have been having a similar problem to you for quite some time. For some reason on some of my grids, when I modify something in the designer, the drop down control seems to break. I discovered that it is actually still there, because if you edit the cell and press up and down keys on the keyboard, it changes items in the drop down control. I just couldn’t see the drop down button. I discovered that this line of code in the designer was causing the problems;
this.comboBoxEditor1.TemplateControl.DropDownButton = null;
Removal of this line and I have my drop down control working again.
Imported from legacy forums. Posted by Peter (had 340 views)