I think that with current screens you have to touch them (but there are screens now where it can feel a hovering finger, but they are not widely used yet, so no). And for save of position of the last touch, you just store that touch in some variables (or arrays, or whatever you like to store stuff in).
EDIT: Just read a little up on hovering fingers, some screens can read a finger very close to the screen, but they count as a touch. Some screens are now able to distinguish between a touch and a hover, but still, not widely used yet.
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