>Is the split at half the page width "fixed" or can it be changed to a user inputted amount, like >one-third or 25%?
Now it is fixed. But why split the line at 1/3 or 1/4? One longer line and one short line will be produced for one original line.
The actual page width generated now is 1/2+1/6 = 2/3 of original page text width. The additional 1/6 is used for finding the space between words.