Making a thin space a breaking space

Question

I routinely surround em dashes with thin spaces. Is there a way that I can make the thin space a breaking thin space so when a line end with an em dash + thin space, the thin space can be the last char. on the line. As a nonbreaking space, the thin space causes unsightly h&j.
Thanks
Jon

Answer 1

Peter,
No, that is "Discretionary Line Break" -- a Zero Width Space (the correct Unicode designation). Since it's a "space", InDesign is allowed to break. Since it's "zero width", you won't see it when it's not active.
A non-joiner is a character which also has no width, but in addition "does nothing" per specification. Its main use is to prevent a ligature: http://en.wikipedia.org/wiki/Zero-width_non-joiner
(Trying to find an example ... hold on. ... An English word that ends with an eff ... drawing a blank and the clock is ticking, I'm going to use a Dutch example.)
In a compound word such as "hofleverancier" ("hof-leverancier", lit. "court supplier"), you would not want an automatic "fl" ligature because you might read "hofle-verancier" instead. Inserting a ZWNJ between the "f" and "l" makes the OpenType engine of InDesign (which processes characters into ligatures) not "see" the exact sequence "f-then-l", since the ZWNJ is a valid Unicode character in its own right.