Async poc

[jeandet]

This is way more responsive than before! I think there are few remaining issues:

• When dragging an event into the trash I get ValueError: badly formed hexadecimal UUID string
• undo stack seems to do stuff in the wrong thread, undoing some operations gives: sqlalchemy.exc.ProgrammingError: (sqlite3.ProgrammingError) SQLite objects created in a thread can only be used in that same thread. The object was created in thread id 140647421552448 and this is thread id 140646568531648.

[pboettch]

This is way more responsive than before! I think there are few remaining issues:

* When dragging an event into the trash I get `ValueError: badly formed hexadecimal UUID string`

* undo stack seems to do stuff in the wrong thread, undoing some operations gives: `sqlalchemy.exc.ProgrammingError: (sqlite3.ProgrammingError) SQLite objects created in a thread can only be used in that same thread. The object was created in thread id 140647421552448 and this is thread id 140646568531648.`

Could you explain which undo-action (What did you undo?) which gave this error?

[jeandet]

Not sure exactly it seems that interleaving drag and drop of events between catalogs and saves seems to generate the error quite easily. I think the undo error was also with a mixed stack of drag end drops deletes and saves.

[jeandet]

@pboettch were you able to reproduce the bug?

[jeandet]

Looks way better now, I also found that stats are not correctly updated on first catalog selection:

• Start Tscat GUI
• select a catalog
• check events count, it is 0
• select another catalog
• select back the first catalog
• check events count, it is populated with the right value (I guess)