Modular computing to me is when you have a LOT of functionality that can be had easily, so to me is modular that Class Viewer can call a web browser or call a text editor. In each case is possible because both allow it, and I think programs that are modular in that they work well with other programs should be cheered.
For instance I default to gedit as the text editor because it takes a line number when called, which means Class Viewer can do the work of looking into a Java file, find where a method is, and then just call gedit or some other text editor which takes that argument to the method. That is fun to me.
Computing in modular ways to me is so natural and know there are others talking same thing, and is kind of different I think to see components like a web browser or a text editor as potential modules but that's how I used them.