It would be very nice for cursors to 'snap' to high d/dt edges when being dragged around. One strawman proposal:
When the mouse pointer is near (in both X and Y) to a high d/dt edge (maybe high d/dt including a low pass filter for current horizontal scale?) that is "large enough" (some percentage of the current vertical display scale?), then the cursor repeatably snaps to the center of that edge.
Holding down a modifier key (shift?) can temporarily override the snapping behavior. (Does this need to change for keyboardless applications? Perhaps a toolbar button, or a checkbox in the 'cursors' menu in the rightclick menu?)
It would be very nice for cursors to 'snap' to high d/dt edges when being dragged around. One strawman proposal: