This should have been changed with the other class
Changing how references are passed around among these dialogs. Adding _addRelease() to the GtkGui class so the code can be shared among the dialogs and the class itself.
Adding buttons to these two dialogs and making them sensitive only when a row is selected.
Fixing references to mbcat.catalog.Catalog static URLs.
main_delete() not part of class
Deriving GroupQueryResultsDialog from QueryResultsDialog