Index: includes/parser/Parser.php
===================================================================
--- includes/parser/Parser.php	(revision 56991)
+++ includes/parser/Parser.php	(working copy)
@@ -1087,6 +1087,7 @@
 	}
 
 	/**
+	 * Processes bolds and italics on a single line.
 	 * Helper function for doAllQuotes()
 	 */
 	public function doQuotes( $text ) {
@@ -1112,18 +1113,22 @@
 						$arr[$i-1] .= "'";
 						$arr[$i] = "'''";
 					}
-					# If there are more than 5 apostrophes in a row, assume they're all
-					# text except for the last 5.
-					else if ( strlen( $arr[$i] ) > 5 )
+					# If there are more than 6 apostrophes in a row, assume they're all
+					# text except for the last 6.
+					else if ( strlen( $arr[$i] ) > 6 )
 					{
-						$arr[$i-1] .= str_repeat( "'", strlen( $arr[$i] ) - 5 );
-						$arr[$i] = "'''''";
+						$arr[$i-1] .= str_repeat( "'", strlen( $arr[$i] ) - 6 );
+						$arr[$i] = "''''''";
 					}
 					# Count the number of occurrences of bold and italics mark-ups.
 					# We are not counting sequences of five apostrophes.
 					if ( strlen( $arr[$i] ) == 2 )      { $numitalics++;             }
 					else if ( strlen( $arr[$i] ) == 3 ) { $numbold++;                }
 					else if ( strlen( $arr[$i] ) == 5 ) { $numitalics++; $numbold++; }
+					else if ( strlen( $arr[$i] ) == 6 ) { 
+							if ($numitalics&1) { $numitalics++; $numbold++; } 
+							else $numbold+=2; 
+					}
 				}
 				$i++;
 			}
@@ -1135,11 +1140,17 @@
 			if ( ( $numbold % 2 == 1 ) && ( $numitalics % 2 == 1 ) )
 			{
 				$i = 0;
+				
+				#These are indexes to the /next/ array entry than the 
+				#one holding the text matching the condition.
 				$firstsingleletterword = -1;
 				$firstmultiletterword = -1;
 				$firstspace = -1;
+				
 				foreach ( $arr as $r )
 				{
+					#Filter the "'''". Separators are on odd positions.
+					#$arr[0] will be an empty string if needed.
 					if ( ( $i % 2 == 1 ) and ( strlen( $r ) == 3 ) )
 					{
 						$x1 = substr ($arr[$i-1], -1);
@@ -1148,7 +1159,7 @@
 							if ($firstspace == -1) $firstspace = $i;
 						} else if ($x2 === ' ') {
 							if ($firstsingleletterword == -1) $firstsingleletterword = $i;
-						} else {
+						} else if ($arr[$i-1] != "") {
 							if ($firstmultiletterword == -1) $firstmultiletterword = $i;
 						}
 					}
@@ -1178,9 +1189,9 @@
 			}
 
 			# Now let's actually convert our apostrophic mush to HTML!
-			$output = '';
-			$buffer = '';
-			$state = '';
+			$output = ''; #Processed text
+			$buffer = ''; #Content if $state is 'both'
+			$state = '';  #Flags with the order of open tags: '|b|i|bi|ib|both'
 			$i = 0;
 			foreach ($arr as $r)
 			{
@@ -1234,6 +1245,21 @@
 						else # ($state == '')
 						{ $buffer = ''; $state = 'both'; }
 					}
+					else if (strlen ($r) == 6)
+					{
+						if ($state === 'b')
+						{ $output .= '</b><b>'; $state = 'b'; }
+						else if ($state === 'i')
+						{ $output .= '\'</i><b>'; $state = 'b'; }
+						else if ($state === 'bi')
+						{ $output .= '\'</i></b>'; $state = ''; }
+						else if ($state === 'ib')
+						{ $output .= '\'</b></i>'; $state = ''; }
+						else if ($state === 'both')
+						{ $output .= '<i><b>'.$buffer.'</b><b>'; $state = 'ib'; }
+						else # ($state == '')
+						{ $buffer = ''; $state = ''; }
+					}
 				}
 				$i++;
 			}
Index: maintenance/parserTests.txt
===================================================================
--- maintenance/parserTests.txt	(revision 56991)
+++ maintenance/parserTests.txt	(working copy)
@@ -5252,19 +5252,17 @@
 </p>
 !! end
 
-# Original result was this:
-# <p><b>bold</b><b>bold<i>bolditalics</i></b>
+# This was the original html, but it has also been
+# <p>'<i>bold'</i><b>bold<i>bolditalics</i></b>
 # </p>
-# While that might be marginally more intuitive, maybe, the six-apostrophe
-# construct is clearly pathological and the result stated here (which is what
-# the parser actually does) is about as reasonable as anything.
+# See bug 18765.
 !!test
 Mixing markup for italics and bold
 !! options
 !! input
 '''bold''''''bold''bolditalics'''''
 !! result
-<p>'<i>bold'</i><b>bold<i>bolditalics</i></b>
+<p><b>bold</b><b>bold<i>bolditalics</i></b>
 </p>
 !! end
 
@@ -7515,6 +7513,90 @@
 <a href="/wiki/Main_Page#section" title="Main Page">#section</a>
 !! end
 
+!! test
+Bold/italic markup handled differently depending on leading whitespace (bug 18765)
+!!input
+'''Look at ''this edit'''s complicated bold/italic markup!'''
+
+<!-- Comment -->'''Look at ''this edit'''s complicated bold/italic markup!'''
+
+<span> '''Look at ''this edit'''s complicated bold/italic markup!'''</span>
+
+<nowiki></nowiki> '''Look at ''this edit'''s complicated bold/italic markup!'''
+
+<!-- Hello world---> '''Look at ''this edit'''s complicated bold/italic markup!'''
+
+{|
+| '''Look at ''this edit'''s complicated bold/italic markup!'''
+|}
+
+'''This was Italic'' this was plain''' and this was bold'''
+but '''This is bold'' this is bold italic''' and this is bold'''
+
+<!-- Wishlist: Breaking because <span> and | are treated as text 
+<span>'''Look at ''this edit'''s complicated bold/italic markup!'''</span> 
+{|
+|'''Look at ''this edit'''s complicated bold/italic markup!'''
+|}
+-->
+!! result
+<p><b>Look at <i>this edit'</i>s complicated bold/italic markup!</b>
+</p><p><b>Look at <i>this edit'</i>s complicated bold/italic markup!</b>
+</p><p><span> <b>Look at <i>this edit'</i>s complicated bold/italic markup!</b></span>
+</p><p> <b>Look at <i>this edit'</i>s complicated bold/italic markup!</b>
+</p>
+<pre><b>Look at <i>this edit'</i>s complicated bold/italic markup!</b>
+</pre>
+<table>
+<tr>
+<td> <b>Look at <i>this edit'</i>s complicated bold/italic markup!</b>
+</td></tr></table>
+<p><b>This was Italic<i> this was plain'</i> and this was bold</b>
+but <b>This is bold<i> this is bold italic'</i> and this is bold</b>
+</p><p><br />
+</p>
+!! end
+
+!! test
+Six quotes
+!!input
+''Italic''''''Bold
+
+'''Bold''BoldItalic''''''Normal
+
+''Italic'''BoldItalic''''''Normal
+
+'''''BoldItalic''''''MoreBoldItalic''
+
+''''''Normal
+!!result
+<p><i>Italic'</i><b>Bold</b>
+</p><p><b>Bold<i>BoldItalic'</i></b>Normal
+</p><p><i>Italic<b>BoldItalic'</b></i>Normal
+</p><p><i><b>BoldItalic</b><b>MoreBoldItalic</b></i>
+</p><p>Normal
+</p>
+!!end
+
+!! test
+Dangling apostrophe with six quotes
+!!input
+''Italic'''Bold''''''Normal'''Bold'''Normal
+!! result
+<p><i>Italic<b>Bold'</b></i>Normal<b>Bold</b>Normal
+</p>
+!! end
+
+!! test
+Too many quotes
+!!input
+I '''like'''''quotes''''''''''' 
+!! result
+<p>I <b>like</b><i>quotes''''''</i><b> </b>
+</p>
+!! end
+
+
 TODO:
 more images
 more tables
Index: RELEASE-NOTES
===================================================================
--- RELEASE-NOTES	(revision 56991)
+++ RELEASE-NOTES	(working copy)
@@ -245,6 +245,8 @@
 
 === Bug fixes in 1.16 ===
 
+* (bug 18765) Increased consistency of bold-italic markup for unbalanced quotes. 
+  Improved representation of six quotes (may break existing markup).
 * (bug 18031) Make namespace selector on Special:Export remember the previous
   selection
 * The svn-version version numbers on Special:Version have been removed