GtkAlignment is an invisible
container used to align a child widget within some
space. It lets you set two factors, each in both the X
and Y direction; the alignment
is 0.0 for left-justified (or top-justified) and 1.0
for right-justified (or bottom-justified). An alignment
of 0.5 centers the child in that direction. The scale factor determines how the
child fills extra space it did not request; if 0.0, the
child fills only its requisition. A scale of 1.0 means
that the child always expands to fill all the available
space. (Clearly, a 1.0 scale factor makes the alignment
factor irrelevant.)
