Fix message compose to identify content iframe the correct way.

mailnews/compose/resources/content/MsgComposeCommands.js

@@ -119,7 +119,7 @@ function ComposeStartup()
 			dump("Created editorShell\n");
 
 			SetupToolbarElements(); //defined into EditorCommands.js
-			contentWindow = window.frames[0]; //Patch to make EditorCommands.js happy...
+            contentWindow = window.content;
 
 			// setEditorType MUST be call before setContentWindow
 			if (msgCompose.composeHTML)
@@ -141,7 +141,7 @@ function ComposeStartup()
 				dump("editor initialized in PLAIN TEXT mode\n");
 			}
 
-			window.editorShell.SetContentWindow(window.frames[0]);
+			window.editorShell.SetContentWindow(contentWindow);
 			window.editorShell.SetWebShellWindow(window);
 			window.editorShell.SetToolbarWindow(window);
 

mailnews/compose/resources/content/messengercompose.xul

@@ -309,7 +309,7 @@ Rights Reserved.
 </toolbox>
 
     <!-- The main mail three pane frame -->
-    <html:iframe type="content" id="content-frame" src="about:blank" name="browser.message.body" flex="100%"/>
+    <html:iframe type="content-primary" id="content-frame" src="about:blank" name="browser.message.body" flex="100%"/>
 
     <!-- Ripped off from navigator.xul; this should be a XUL fragment! -->
     <box align="horizontal" id="status-bar">