Make arguments like Context.GrobName accessible as symbol lists

Documentation/snippets/new/making-an-object-invisible-with-the-transparent-property.ly

-\version "2.17.5"
+\version "2.17.6"
 
 \header {
   lsrtags = "rhythms, simultaneous-notes, tweaks-and-overrides"
 
   texidoc = "
 Setting the @code{transparent} property will cause an object to be
 printed in @qq{invisible ink}: the object is not printed, but all its
 other behavior is retained.  The object still takes up space, it takes
 part in collisions, and slurs, ties and beams can be attached to it.
 
 
 This snippet demonstrates how to connect different voices using ties.
 Normally, ties only connect two notes in the same voice.  By
 introducing a tie in a different voice, and blanking the first up-stem
 in that voice, the tie appears to cross voices.
 
 "
   doctitle = "Making an object invisible with the 'transparent property"
 }
 
 \relative c'' {
   \time 2/4
   <<
     {
-      \once \override Stem transparent = ##t
-      \once \override Stem length = #8
+      \once \override Stem.transparent = ##t
+      \once \override Stem.length = #8
       b8 ~ b\noBeam
-      \once \override Stem transparent = ##t
-      \once \override Stem length = #8
+      \once \override Stem.transparent = ##t
+      \once \override Stem.length = #8
       g8 ~ g\noBeam
     }
     \\
     {
       b8 g g e
     }
   >>
 }