Fix for 18244. Don't load messages if splitter between thread and message pane is collapsed.

reviewed by hangas.

mailnews/base/resources/content/commandglue.js

@@ -347,18 +347,36 @@ function ToggleMessageFlagged(treeItem)
 	messenger.MarkMessageFlagged(tree.database, treeItem, !flagged);
 }
 
-function ThreadPaneSelectionChange(selectedElement)
+//Called when the splitter in between the thread and message panes is clicked.
+function OnClickThreadAndMessagePaneSplitter()
+{
+	var collapsed = IsThreadAndMessagePaneSplitterCollapsed();
+	//collapsed is the previous state so we know we are opening.
+	if(collapsed)
+		LoadSelectionIntoMessagePane();	
+}
+
+//Called when selection changes in the thread pane.
+function ThreadPaneSelectionChange()
+{
+	var collapsed = IsThreadAndMessagePaneSplitterCollapsed();
+
+	if(!collapsed)
+	{
+		LoadSelectionIntoMessagePane();
+	}
+}
+
+//takes the selection from the thread pane and loads it into the message pane
+function LoadSelectionIntoMessagePane()
 {
 	var tree = GetThreadTree();
 	
 	var selArray = tree.selectedItems;
-	dump('In ThreadPaneSelectionChange().  Num Selected Items = ' + selArray.length);
-	dump('\n');
 	if ( selArray && (selArray.length == 1) )
 		LoadMessage(selArray[0]);
 	else
 		ClearMessagePane();
-
 }
 
 function FolderPaneSelectionChange()

mailnews/base/resources/content/messenger.xul

@@ -541,7 +541,9 @@ Rights Reserved.
 		  <tree id="threadTree"/>
 		 </html:div>
 
-	    <splitter id="gray_horizontal_splitter" collapse="after" persist="state"/>
+		<!-- if you change this id, please change GetThreadAndMessagePaneSplitter() -->
+	    <splitter id="gray_horizontal_splitter" collapse="after" persist="state"
+							 onclick="OnClickThreadAndMessagePaneSplitter()"/>
 			
     	<!-- message view -->
 		  <html:iframe flex="3" style="height:0px" name="messagepane" src="about:blank"/>

mailnews/base/resources/content/msgMail3PaneWindow.js

@@ -35,6 +35,8 @@ var messageDSProgID        = datasourceProgIDPrefix + "mailnewsmessages";
 
 var gFolderTree;
 var gThreadTree;
+var gThreadAndMessagePaneSplitter = null;
+
 var gCurrentLoadingFolderURI;
 var gCurrentLoadingFolderIsThreaded = false;
 var gCurrentLoadingFolderSortID ="";
@@ -357,6 +359,26 @@ function GetThreadTreeFolder()
   return tree;
 }
 
+function GetThreadAndMessagePaneSplitter()
+{
+	if(gThreadAndMessagePaneSplitter) return gThreadAndMessagePaneSplitter;
+	var splitter = document.getElementById('gray_horizontal_splitter');
+	gThreadAndMessagePaneSplitter = splitter;
+	return splitter;
+}
+
+function IsThreadAndMessagePaneSplitterCollapsed()
+{
+	var splitter = GetThreadAndMessagePaneSplitter();
+	if(splitter)
+	{
+		var state  = splitter.getAttribute('state');
+		return (state == "collapsed");
+	}
+	else
+		return false;
+}
+
 function FindMessenger()
 {
   return messenger;

mailnews/base/resources/content/threadPane.xul

@@ -30,9 +30,11 @@ Rights Reserved.
 >
 
 <tree datasources="rdf:null" id="threadTree" style="width: 100%; height: 100%"
-	  		  onselect="top.ThreadPaneSelectionChange(event.target); document.commandDispatcher.updateCommands('tree-select');"
+	  		  onselect="top.ThreadPaneSelectionChange(); document.commandDispatcher.updateCommands('tree-select');"
 			  onblur="goOnEvent(this,'blur')"
 			  containment="http://home.netscape.com/NC-rdf#MessageChild">
+			  allownegativeassertions="false"
+              coalesceduplicatearcs="false">
 
   <template>
   	<rule>
@@ -41,7 +43,6 @@ Rights Reserved.
 			 Status="rdf:http://home.netscape.com/NC-rdf#Status"
   			 Flagged="rdf:http://home.netscape.com/NC-rdf#Flagged"
   		     Priority="rdf:http://home.netscape.com/NC-rdf#Priority">
-  		     
 	  		<treerow>
 				<treecell value="rdf:http://home.netscape.com/NC-rdf#Thread"/>
 				<treecell indent="true" value="rdf:http://home.netscape.com/NC-rdf#Subject"/>