Feature request: create point with arrow keys rather than mouse

[JBracewelll]

We have to digitize KM curves such as the one linked below and it is very difficult to make manual data points in a straight line so that the x or y values do not accidentally increase. We also cannot use the automatic extraction as filing by x values causes errors when there are multiple rows at the same x value (when there is a vertical line down). Any help greatly appreciated.