My idea refers to previously existing files (diagrams) and those which were created on Gliffy directly (not via Google Drive);
Meaning, "Gliffy - to - Drive" direction.
Instead of downloading *.gliffy files to the desktop and then uploading them to Google Drive(which is annoying); or getting to Google Drive and open file from there.
You could just add a new menu entry, like:" Export to Drive'. When chosen, A Google Drive folder tree would be displayed. Then I would pick a folder to save my file.
In this case I'll be able to save all my diagrams directly to Drive without downloading and uploading process.
That all, thanks for your attention. ^_^