diff --git a/runtime/doc/eval.txt b/runtime/doc/eval.txt
index 12ea9c8..8934215 100644
--- a/runtime/doc/eval.txt
+++ b/runtime/doc/eval.txt
@@ -1932,6 +1932,7 @@
 shellescape( {string} [, {special}])
 				String	escape {string} for use as shell
 					command argument
+shiftwidth()			Number	effective value of 'shiftwidth'
 simplify( {filename})		String	simplify filename as much as possible
 sin( {expr})			Float	sine of {expr}
 sinh( {expr})			Float	hyperbolic sine of {expr}
@@ -3754,10 +3755,10 @@
 		Like |input()|, but when the GUI is running and text dialogs
 		are supported, a dialog window pops up to input the text.
 		Example: >
-			:let n = inputdialog("value for shiftwidth", &sw)
-			:if n != ""
-			:  let &sw = n
-			:endif
+		   :let n = inputdialog("value for shiftwidth", shiftwidth())
+		   :if n != ""
+		   :  let &sw = n
+		   :endif
 <		When the dialog is cancelled {cancelreturn} is returned.  When
 		omitted an empty string is returned.
 		Hitting <Enter> works like pressing the OK button.  Hitting
@@ -5331,6 +5332,23 @@
 		    :call system("chmod +w -- " . shellescape(expand("%")))
 
 
+shiftwidth()						*shiftwidth()*
+		Returns the effective value of 'shiftwidth'. This is the
+		'shiftwidth' value unless it is zero, in which case it is the
+		'tabstop' value.  To be backwards compatible in indent
+		plugins, use this: >
+			if exists('*shiftwidth')
+			  func s:sw()
+			    return shiftwidth()
+			  endfunc
+			else
+			  func s:sw()
+			    return &sw
+			  endfunc
+			endif
+<		And then use s:sw() instead of &sw.
+
+
 simplify({filename})					*simplify()*
 		Simplify the file name as much as possible without changing
 		the meaning.  Shortcuts (on MS-Windows) or symbolic links (on