pkgsrc-wip, as the program has changed a lot. So:
AfterStep is a window manager for the Unix X Window System. Based on the
look and feel of the NeXTStep interface, it provides end users with a
consistent, clean, and elegant desktop.
Some of the distinguishing features of AfterStep compared to other window
managers are its low usage of resources, stability and configurability.
for a possessive (like her, his, whose, their, and its).
Note that I didn't check for proper use of "its" (when it should
be "it is" or "it has" instead).
I also saw over 15 other grammar or punctuation problems, but not
fixed in this commit.