235747 was opened as a DSF-GDB parity issue and it is currently in the high-priority bucket. The description states:This is not necessarily very practical but for feature equivalence, DSF-GDB should implement it.
I suspect that is correct--that editing register groups is a rarely used feature of the CDT debugger (CDI-GDB). If that's true, then this issue should be lowered in priority, as per the discussions we've had on this topic recently. If you know people are using it, or are very confident they are, please speak up.