[isabelle-dev] Extra line spacing

[Makarius]

Just a side-remark on extra line spacing in Isabelle/jEdit. The jEdit guys 
have introduced a new option for that some time ago:

   Global Options / Text Area / Extra vertical line spacing (in pixels): 0

The author probably did not intend this, but it happens to work with 
negative values, too. I just looked a bit over the implementation of both 
the jEdit and the Isabelle/jEdit text rendering engine, to see if this 
makes sense, which seems to be the case.  (My renderer already uses an 
explicit clip rectangle to keep text precisely within its specified 
space.)

Current Isabelle/1d122af2b11a merely ensures that the pretty text area 
(for Output or Tooltips etc.) observes the same jEdit property.


I am presently using myself IsabelleText 18px -2px line spacing, and so 
far it looks good, more like regular Deja Vu without the tall glyphs we 
have from TeX.

(This was once on the list of remaining reasons for Proof General.  Is 
there still anything left on that?)


 	Makarius