Hi,
On the Mac double clicking a tgd file in the Finder when TG2 is not already running will open TG2 but not open the file. I can't remember if it works or not when you drop a file on the app icon if the app isn't running, but I suspect not. Both will work if the app is already running.
I have sorted this out now, and this stuff will work as expected with the next TP release.
Giantsteps, when you say you're paranoid about command-o not working is this because you've had problems with it, or just that the fact TG2 doesn't open files in the above situations is giving you the willies? If it's the latter, don't worry because the two things ( command-o and double clicking ) are actually completely unrelated. What happens when you double click a file in the Finder is that the Finder starts the app which should open the file and then sends a thing called an AppleEvent to the app telling it which file to open. When TG2 was starting up it wasn't holding on to that AppleEvent, for various complex reasons, and so it didn't know it was supposed to open a file after it finished starting up. This is what is fixed for the next TP release ( and in current Mac alpha versions ).
Opening files once TG2 has started up should work fine, and I'm not aware of any bugs relating to that. You can use command-o or choose the Open item from the File menu to bring up an Open File dialog and choose a file to open. If TG2 has already started up then you should find you can double click tgd files in the Finder, or drop them on the app icon, and they will open.
Regards,
Jo