Wonderful, thank you!
It's a bit of a roundabout method, but here's exactly what we wanted to do and how I accomplished it:
Goal: We have a custom field called "Client" which indicates which customer an issue is for. We wanted to add a column to indicate the "temperature" of the customer. Only managers may edit the value, and when they do we want it to update that value for any issues with the same "Client" value to the new one.
Initial Solution: Because a Dropdown Listbox only allows you to specify a list of text values, we started off with "Green", "Yellow", and "Red". I then added a database trigger for inserts and updates on gemini_customfielddata. If the value modified has a customfieldid of our "temperature" and the new value isn't blank, we then join to gemin_customfielddata 3 times - once to get the Client of the issue, next to get all of the issues with the same Client, and last to get those issues' Temperature records.
Worked like a charm!!
But.. we still wanted it to be fancy and show an image like the one in my OP. After Simran's post (thanks again!) I played around with a Rich Text Custom Field. Everything was looking good - I could reference the local image files and we could see the image in the Issues List and View Screens. However, there was a major bummer - you can't edit Rich Text values Inline.
Final Solution: So, we decided that we would add one more Custom Field (Dropdown Listbox) that would have just the names of the colors. I then modified the trigger to look for changes to this "TemperatureName" field and then perform pretty much the same join operations to get the "TemperatureImage" of that issue and any others of the same client and update their value like so (we decided we wanted to have the image indented by one tab for viewing so there's some extra html in there):
SET tmpimg.fielddata = <p style="padding-left: 30px;"><img style="float: left;" title="Temperature" src="/images/Temperature_' + tmptxt.fielddata + '.png" alt="Temperature" width="16" height="16" /></p>
Problem solved =)
