1) It may be noted that the tip of the drawer closest to the user is at the same location as the end of the user-proximal drawer guide. This is not really a coincidence: In X, the end of the guide, and the end of the drawer, are at the edge of the desk because that's as far that way as we want any of this hardware. (In the closed position.) In Y, the two things are at the same height because the lower of the two is the limit of the "thigh wiggle room", which we wish to maximize; further, to optimize other qualities, the height of the end of the drawer guide is made as low as possible. 2) Longer distances between the drawer-guide pins generally; give better control and better behaved movement. 3) It is nearly impossible with this control geometry to have a keyboard at the right height for operation with the drawer in both the closed and open position, while still giving a large amount of leg clearence with the drawer in the closed position.