Linebreaks in TOC

I have a TOC made of two columns, with headings, dotted leaders and
page-numbers. In a certain case, a line-break cause the page number to be
stretched out in one line. Found three cases:

1. The line does not need a line-break. This is okay.

Blah blah blah bl.......12

2. The line needs a line-break, but the header is more than one row. This
is okay too.

Blah blah blah blah blah
blah blah...............12

3. There is enough room for the header, but not for the page-number.

Blah blah blah blah blah..
1                        2

If there is no room for the page number, the last word in the header should
be moved to the next line, like this:

Blah blah blah blah
blah....................12

This has been very hard to achieve. Is it even possible to make such an
expression in FO syntax?

Gustaf


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