As nice as the colored-pencil functionality is*, I'd really like to be able to directly keep track of _sets_ of remaining possibilities in puzzles where each cell can have many different possible contents. I noticed in Enlightenment that the corners of cells can be activated (though I haven't yet divined the purpose of doing so). Would it be possible to add mini-corner cells to Sudoku and Co. to put smaller numbers in? Sorry if there's already some way to do this that I've somehow managed to miss, and thanks!
*not that I'd complain if someone added erase-all-of-color buttons. ^_^b
I fear we need a fundamental change of the system to be able to enable notes like that. Although we would like to enable it at some point, it will probably be a long term thing.
To have erasers per color is a less significant change and it is somewhere on our TODO list, but I don't know when we will get to it.