I've always been more unixy-minded in wanting to keep them separate,
and special-purposed. We did already budge on that by allowing the
file browser to be docked, though.
The reason we don't have the file browser docked by default is that it
uses a bunch of resources in the beginning when it's querying history
for each visible file. The DAG also has overhead, which is why I
preferred having it separate -- startup time is important.
The View->DAG menu item already exists ~ in that sense it's already
integrated. Do you mean that you'd like it to be dockable into the
main UI like the other tools? If so, it wouldn't be enabled by
default, and you'd have to configure to enable it (just like the
cola.browserdockable feature).
Grepping for the places where cola.browserdockable is used will reveal
the spots to change to enable that feature, in case anyone wants to
give it a stab. Otherwise, please feel free to submit a feature
request since it should be fairly straightforward to add.
cheers,
David