Recommendation for multi-platform, portable, learning mode Git GUI?

Question

Any recommendations for a good Git GUI. Should ideally have the following characteristics:

1. Not be very limiting i.e. can support relatively complex functions e.g. rebase, no-ff

2. Shows Git commands being executed in a "learning mode", especially for commands with lots of options

3. Preferably portable (does not require windows installation OR even if only windows, works like a portable application)

4. Preferably multi-platform (so there is no learning curve between my linux machine and windows laptop.

Answer 1

Git extensions supports almost all operations (for example, it supports interactive rebase). It also shows command line used for the launched operation.

Update: This is incorrect: Unfortunately it is Windows-only. It may work on linux: Git Extensions runs on multiple platforms using Mono.