@Outlaw Programmer said:
In fact, I think pretty much any time you need to come up with your own type of GUI control you're probably on the wrong path. I remember a project where a developer worked for a few weeks on a drop-down control, except you could select multiple values. Each value in the drop-down had a checkbox next to it, indicating that it's selected. It kind of worked, but when the drop-down part was closed (i.e. it shrinks back down to 1 line), only the first choice would be visible; You couldn't tell what was selected without opening the drop-down again and scrolling through the (hundreds) of options. I tried to tell them that there was already a control that was built for this purpose, the List Box (JList in Java), but the managers just liked the look of drop-down combo boxes.
At my previous job, one of our applications had a lot of editable combo boxes for data entry. The customer didn't like them for some reason, and they wanted us to replace them with text fields that showed a popup menu on right-click with the choices. We tried to talk them out of it (we should follow UI standards, etc.), but they didn't care. We got out of it by giving them a ridiculous time estimate (with associated cost), and they decided it wasn't worth it.