When you have been writing XPage applications for a while you may notice that you start using the source pane a lot more then the design pane. Sometimes it is so you can copy/paste parts of the markup from one place to another, sometimes so you can duplicate a bit of code but sometimes you need to because what your trying to do isn’t accessible from the design pane.
A case in point is the combobox control. Add a combobox to your page and then on the ‘values’ tab of the properties box add in a number of different values. The only options you have here is the value text and the actual value. If you go to the source pane and click on one of the SelectItem controls that were generated when you added the values on the values properties box you will see that the SelectItem has it’s own set of properties so you can do things like add a ‘rendered’ property to determine if a particular value should even display as an option to the end user of the application.
So don’t forget to check out the source…