So I was working on an Eclipse form-based editor the other day when I came across a rather interesting UI puzzle. In my model, I have an enumeration field. Depending on what the user selects, certain other detail fields become relevant and need to be shown. Previously, I have solved this problem by putting the master combo field first followed by a details frame that contains all the detail fields and is updated when combo selection is made. That worked relatively well when that master-details block was in a section by itself, but as soon as it got surrounded by other fields, it started to become difficult to tell at a glance that the combo and the frame belonged together and were separate from other fields in the section.
See for yourself...
Besides dancing around the problem by adding a little white space above the master combo or putting the entire master-details block into a section by itself, one other approach occurred to me. Here, the master and detail fields are next to each other and enclosed together in a frame.
Both approaches have their pluses and minuses. The second approach does make it more clear that master and details are tied together, but we loose the ability to identify what is master and what is details. My question for the UI experts out there is how do you typically render such master-details blocks? Do you use one of these approaches that I described? Something else entirely?