I assume you're using 1.1.391 (the latest public release), and that the " - MGH" indicates you have defined an Eclipse working set with that name and selected it (e.g. in the dropdown menu from the down-arrow on that dialog).
For the benefit of others who may not have found this dialog yet, it's on the standard "Navigate" menu and also the standard toolbar (white "C" in blue circle).
It apparently searches the filenames within your projects (optionally limiting this to projects in your current working set), but I haven't yet found a way to make it take the package into account in its lookup, nor to display it.
I am interested to know more about the "Workspace matches" part of your screenshot. So far I haven't managed to get this on mine.
And can someone explain the rather cryptic "TZ = TimeZone" part of the dialog text?