Bug 123487

I have a document that starts with a guarded section, then has a small unguarded section, and then another guarded 
section.  I create a fold that starts in the first guarded section and ends in the second guarded section.  When I 
collapse the fold I get a box representing the fold, as expected.  The background surrounding the box is shaded, as 
the fold box is sitting inside a guarded region of the file.  However, the GUI displays a small white strip, 2 pixels 
wide, to the left of the box.  Ordinarily this wouldn't be noticeable in a non-guarded section, as the background 
would be white anyway.  But it's very noticable in the guarded section case and makes the display look messy.  Perhaps 
these pixels should be transparent so you get the spacing you want, but allow the background to show through?  Or 
maybe this white space wasn't intended to be there?  Just to be clear, I'm talking about pixels to the left of the 
box; I'm not suggesting the background pixels in the box itself should be transparent.