Support paragraph-local tab stops

[Yuan Fu]

The motivation is variable pitch table in Emacs. Right now, although you can use tab stops to properly align a table, because the tabs stops are buffer-global, all the tables in a buffer has to share the same tab stop configurations. Then a good tab stop configuration for one table could mess up the alignment for another table. Let me explain:

In a word processor, if I have two tables. One with short headers, one with long headers. The image below shows the two tables and the blue arrows on the ruler represents the tab stops for the first table.

Here, the blue arrows show the tab stops of the second table:

As show above, the second table has longer tab stops since they have longer headers.

In Emacs, both table would have to use long tab stops, and the first table with short headers would waste a lot of space. In order to set proper tab stops, you have to go through the whole buffer and use the longest header for each column.

Word processors doesn’t have this problem because they have paragraph-local tab stops, so each table can have their own tabs stops. I wonder if Emacs can do the same. Can we add a text property that points to a list that specifies the tabs stops to use? Is that possible?

Yuan