![geometer geometer](http://acypher.com/wwid/Chapters/13Sketchpad1.jpg)
(Windows) Sketchpad no longer occasionally hangs with a flickering toolbox after sudden movements of the mouse wheel.Defining a coordinate system by measurements now correctly determines the horizontal unit scaling from the first selected measure and the vertical unit scaling from the second selected measure.This fixes calculations such as 1/y (= +infinity) and arctan (x/y) (= pi/2) for a = (0, 0). A point on a horizontal axis in a coordinate system now correctly considers its y-value to be +0.0 rather than –0.0.If the program speed in GSP 4.06 is notably slower than in your previous version, change the Anti-Aliased Graphics setting from "Always" either to "When Speed Permits" or to "Never," as you prefer.
![geometer geometer](http://4.bp.blogspot.com/_qHsSKa-iP_c/StPzEaJdr3I/AAAAAAAAABY/KWr-1hOajvk/w1200-h630-p-k-no-nu/Geometer+Sketchpad+1.jpg)
Use the System panel of Advanced Preferences to view or change this setting. (This change will not affect the behavior of installations of 4.04 or 4.05, but will affect older Sketchpads and new installations on machines on which Sketchpad has not been previously used.) Anti-aliased graphics improve the appearance of Sketchpad objects, at the expense of slower operation of the program. (Windows and Mac OS X) The new anti-aliased graphics introduced in GSP 4.04 are now enabled, rather than disabled, by default.