Gettys’ points still relevant today
He talks a bit about the GUI wars. But back then, it wasn’t GNOME and KDE; it was OpenLook and Motif.
As a result, I believe that any toolkit that does not allow full customization or cannot be customized to look like the other toolkit’s default style should be considered broken. The sooner people accept the premise that all toolkits should be configurable to closely match other styles (and future styles) as a minimum of all future X toolkit development, the better, and that the less grief we will all have.
Many of his other points also remain equally relevant today. Take a look at it, particularly if you’re involved with X, toolkits, WM’s, DE’s or anything along those lines.