Another VERY good point, with a good hint.
We’re about to release a "business" version of Tabbles and a "student" one. For the first one (and maybe the second as well) we’re aiming to have a document versioning system( which we hope to develop sometime in Q4 2009).
Anyway we initially discarded the possibility of a sub-versioning: we thought that getting into files and comparing them would be a mess. Now, we’re not too keen in interfacing Tabbles with an external app at this time (as we prefer to develop the thing ourselves and hold all the rights to sell it), but we’ll definitely have a look at Tortoise.
One thing: Tabbles is born as a tool for the average office-job guy. We ended up with a database interfacing and visualization tool. We already had a couple of suggestions about "plugins for this or that software"… we may definitely look into that at some point! 🙂
Thanks for the good hint!