View structure's fetch dbrefs progress bar is misleading

The "Fetch DBRefs" progress bar shown in the Alignment window after the user selects 'View Structure' doesn't actually imply that anything else is going to happen after the query has finished.

Please fix the interaction so:
1. Selecting 'View structure' brings up a new dialog box indicating what the query is doing (ie searching for structures for all sequences, one seuqence in particular or currently selected set), with a progress bar.
2. Once progress bar finished, the dialog updates itself with appropriate options.