Doc: Added documentation for fill-line line-width (issue 583340043 by address@hidden)

[davidgrant . no]

Reviewers: ,

Message:
Doc: Added documentation for fill-line line-width

Added short descriptions and examples to Notation Reference.

Suggestions for additions to documentation following this thread on
lilypond-user:
https://lists.gnu.org/archive/html/lilypond-user/2020-01/msg00081.html

Description:
Doc: Added documentation for fill-line line-width

Added short descriptions and examples to Notation Reference.

Please review this at https://codereview.appspot.com/583340043/

Affected files (+23, -0 lines):
  M Documentation/notation/text.itely
  M scm/define-markup-commands.scm


Index: Documentation/notation/text.itely
diff --git a/Documentation/notation/text.itely  
b/Documentation/notation/text.itely
index  
ced0bca8ca2790dd034e493dc5fdafe20bdf414c..507d16aff3b369663960f035e69a6b21c0520013  
100644
--- a/Documentation/notation/text.itely
+++ b/Documentation/notation/text.itely
@@ -1064,6 +1064,24 @@ multi-line text or any other markup expression:
 }
 @end lilypond

+@cindex text, line width
+@cindex markup text, line width
+
+Elements may be spread to fill any specified width by overriding
+the @code{line-width} property.  By default it is set to
+@code{#f} which indicates the entire line:
+
+@lilypond[quote,verbatim]
+\markup {
+  \column {
+    \fill-line { left center right }
+    \null
+    \override #'(line-width . 30)
+    \fill-line { left center right }
+  }
+}
+@end lilypond
+
 @cindex wordwrapped text
 @cindex justified text
 @cindex text, justified
Index: scm/define-markup-commands.scm
diff --git a/scm/define-markup-commands.scm b/scm/define-markup-commands.scm
index  
9bd183789a3e13750571ccab2268f17b01d7210a..5463d3b4bba04836638eb4c2c5d3bd6a0db1484d  
100644
--- a/scm/define-markup-commands.scm
+++ b/scm/define-markup-commands.scm
@@ -1569,6 +1569,11 @@ If there are no arguments, return an empty stencil.
       }
       \\line { across the page }
     }
+    \\null
+    \\override #'(line-width . 50)
+    \\fill-line {
+      Width explicitly specified
+    }
   }
 }
 @end lilypond"