since g-s-m provides a way to see the usage of the partitions but not in which folder is consumed and baobab the way around (per folder usage but not per partition) some kind of integration would be really useful

maybe just a simple context menu item to launch baobab with the selected partition

or maybe an arrow in the left that when you expand it displays the partition folders list ordered by size (the same way as baobab displays it)

the second one would be easy if baobab was a widget, and at least for me it's more nice an useful :)