Here is the new modifiew key behaviour :
* CONTROL while dragging a point :
slow down 20x the point move (i.e. 1pixel of cursor move move the control point by 0.05px)
* SHIFT while dragging a point :
snap the point to the following elements, on a "use nearest solution" method :
o Diagonal curve editor :
+ top bound,
+ bottom bound,
+ identity (diagonal) line,
+ same Y than previous point,
+ same Y than next point,
+ line made by the previous and next point ; this will help to create linear parts in the curve more easilly
o Flat curve editor (when moving a point) :
+ top bound,
+ bottom bound,
+ identity (horizontal) line,
+ same Y than previous point (or last point if you move the first point),
+ same Y than next point (or first point if you move the last point
o Flat curve editor (when moving a tangential handle) :
+ 0.0, 0.35, 0.5, 1.0 values
0.35 is the default handles value and does create an smooth "diagonal" transition between points.
