Xlib provides many convenience functions to make it simpler to change
attributes of X resources. ProXL doesn't provide these functions, since
the put_*_attributes/2 procedures are quite simple to use, so there
is no need for them in Prolog. For example, Xlib provides separate
functions to change each GC attribute, as well as a general function
that can change all the attributes of a GC at once; ProXL only provides
the procedure to change all attributes at once, since it is easy to
use. Leaving out all these unnecessary convenience functions makes ProXL
simpler and smaller than Xlib.