Currently, to change a splitter bit assignment, you have to select the bit with the mouse and then click on the position you wish to map it to. The second part can be done with the keyboard via 'none,0,1,2,etc.). The first can only be done by a mouse click.
It would make it easier to edit a splitter if one could press the desired key (none,0,1,2,3,etc) when over the desired bit and then press the up/down arrow to enter the change and move to the next up/down position. This would eliminate the mouse-click/key-press/mouse-move sequence that, when dealing with larger splitters, is tedious. With the proposed change, one can zoom through the changes very quickly and will not have to look at the screen to confirm position as is required when using the mouse.
related: When changing the bit-size or fan-out of a splitter, it would be nice to be able to specify to keep the current ordering as much as possible rather than re-assign it automatically. Sometimes, I need to add one extra bit or fan-out on large splitters and then am forced to go through all the bits to remap them, even if only one bit was effectively appended.
Little niceties that improve, IMHO, the ergonomics.