Having the project shown in a tree would be nice addition expecialy in combination with #1, #2 and #3.

[*] MyGame [ update ] [ open ]
|- [*] Kha [ update ]
|   |- [x] Haxe [ update ]
|   |- [ ] Kore
|- [x] MySubRep [ update ]

In my example above only the marked child projects would be updated (not sure if or when this makes sence).
But in conjunction with #1 you could have a climps which of your subprojects are up-to-date.
With #2 you could select different origins for different subprojects.
With #3 you could select different branches for different subprojects.