As a followup, attached is a changeset for Pharo8 with a simple implementation of horizontal scrolling. I tried to keep it minimal.
It adds startColumnIndex var to FTTableContainerMorph which is being set when�� FTTableContainerMorph>>adjustToHorizontalScrollBarValue: is triggered.
The�� main change is in #calculateColumnWidths - it starts distributing space width from the startColumnIndex to ensure this area gets most visibility. If startColumnIndex is 0, it reverts to old (current) behavior - trying to draw columns starting from the first one as space permits.
The scrolling thus jumps to a beginning of the column and I'm not particularly proud of the thing, but it is better then nothing and suits my immediate needs. So may be it is worth a look for those who are interested.
To try one can use an example:
FTExamples exampleTableHorizontalScroll
Or even set trialHSB := true in FTTableMorth>>initialize (like I have to enable it everywhere by default)
(as a side note the list is very quiet, compared to what it used to be years ago)