Hmmm... I am clearly interpreting things differently as I look at the OP's request.
does anybody has a solution for dragging an object within a group to prevent moving faster than the mouse cursor?
My version does this - the dragged object is in a group and syncs with the mouse movement.
i use flexible layout and set a rectangle within a group. if i move this rectangle, it moves faster than my mouse cursor.
this happens only within a group, setting the group to be scaled.
By putting the original group in another group it satisfies the flexible layout request as well as the drag element syncing with mouse. I am not interpreting a nested group as being proscribed in the OP's request - the net effect matches his request. No other restrictions are spec'd.
Maybe @strmiska will chime in here at some point in the upcoming week and offer his thoughts.