Currently axes have one kind of grid (let's call it major grid).
It would be good if there were minor grid, too.
Here is the idea- these (grid) lines which are drawn where marks values are displayed are major grids (for example you have a a chart with X values between 0 and 10 and on the X scale it is written 0,1,2,3....10.)
Minor grid is between the major grid (having the same kind of properties as the major grid, so the user could use a lighter colour). These grid lines could correspond to 0,1; 0,2; 0,3; .... 0,9.... or 0,2;0,4;0,6;0,8.
Could this be done, it very convenient?