There is already some documentation of the editing tool available. see http://doc.robofont.com/documentation/tools/editing-tool/
* straight line to curve:
– alt+drag the straight line
– alt+drag one of the oncurve points
* deleting bcps:
– delete a bcp will remove both bcps
– alt delete a bcp will algign the bcp on top of the oncurve point
RoboFont tries to bundle similar actions to one and the same shortcut.
Bcp handle modifications are mostly all bundle with the “command” key.
* modifying curves by grabbing the curve:
– only dragging: moving all points
– command + drag: adjusting the bcp handles
– shift + drag: drag the points on 0° 45° or 90°
– alt + drag: un-smooth the oncurve points and move the bcps only
– shift + alt + drag: lock the bcp on 0° 45° 90°