Since all these curve types are similar (i.e. all use focal points), it would be helpful if the drawing options were similar for each one. Currently they all seem to have different drawing options, which is confusing. For example, the Parabola command has some of the most useful drawing options, allowing you to define either the vertex and direction, or the vertex and the focus, or focus and direction, and giving you the option to mark the focus, and/or draw only half of the object. These options are excellent. Whenever you draw a parabola, you always see the focal point as a drawing aid, which is extremely helpful. I wish the Ellipse command also had these same options. ‘Ellipse: from foci’ is the only way to view the foci while you’re drawing an ellipse, but you really ought to be able to view the foci using any of the ellipse drawing options. ‘Ellipse: diameter’ is a similar drawing approach as ‘Parabola by vertex’, but you cannot see the foci in the Ellipse version, nor does it give you the option of marking the foci when it is done drawing. You really need to be able to see the foci while you’re drawing any of these objects (the focal points are the reason engineers use these curves! 
). I would also like the option of drawing only half of an ellipse (or actually, a quandrant), similar to the options of the Parabola). Also, the ‘Ellipse: by corners’ drawing approach could be a method to draw parabolas as well. Btw, all these great options could be used for drawing hyperbolas too :).
Oh yeah, one more thing: would be fantastic if the History command worked with these curves, such that you could move one of the focal points and the curve would update for you. And btw since these curve types are all related, I would maybe suggest putting them all in one unified window. I’ll stop now
cheers! -d