Index: /FCKeditor/trunk/_whatsnew.html
===================================================================
--- /FCKeditor/trunk/_whatsnew.html	(revision 2169)
+++ /FCKeditor/trunk/_whatsnew.html	(revision 2170)
@@ -73,4 +73,6 @@
 		<li>[<a target="_blank" href="http://dev.fckeditor.net/ticket/2320">#2320</a>] Fixed the issue
 			where the Find/Replace dialog scrolls the entire page.</li>
+		<li>[<a target="_blank" href="http://dev.fckeditor.net/ticket/1645">#1645</a>] Added warning message
+			about Firefox 3's strict origin policy.</li>
 	</ul>
 	<p>
Index: /FCKeditor/trunk/editor/fckeditor.html
===================================================================
--- /FCKeditor/trunk/editor/fckeditor.html	(revision 2169)
+++ /FCKeditor/trunk/editor/fckeditor.html	(revision 2170)
@@ -31,4 +31,35 @@
 	@Packager.RemoveLine -->
 	<script type="text/javascript">
+
+// #1645: Alert the user if opening FCKeditor in FF3 from local filesystem
+// without security.fileuri.strict_origin_policy disabled.
+if ( document.location.protocol == 'file:' )
+{
+	try
+	{
+		window.parent.document.domain ;
+	}
+	catch ( e )
+	{
+		window.addEventListener( 'load', function()
+			{
+				document.body.innerHTML = '\
+					<div style="border: 1px red solid; font-family: arial; font-size: 12px; color: red; padding:10px;">\
+						<p>\
+							<b>Your browser security settings don\'t allow FCKeditor to be opened from\
+							the local filesystem.<\/b>\
+						<\/p>\
+						<p>\
+							Please open the <b>about:config<\/b> page and disable the\
+							&quot;security.fileuri.strict_origin_policy&quot; option; then load this page again.\
+						<\/p>\
+						<p>\
+							Check our <a href="http://docs.fckeditor.net/FCKeditor_2.x/Developers_Guide/FAQ#ff3perms">FAQ<\/a>\
+							for more information.\
+						<\/p>\
+					<\/div>' ;
+			}, false ) ;
+	}
+}
 
 // Save a reference to the default domain.