Default Drawing of Line/Curve

The usual mode of drawing with points is to draw with curved points and use the Ctrl key to draw a line. This may be undesirable for some art. You can use this button to switch the way that operates – pressing it will cause drawing to default to a line, and the Ctrl key will cause points to be a curve. Note that using the Shift key to make a line constrained to 15 degree angles will work either way – you can constrain the line angle as long as you are not making a curve.