Index: editor/plugins/autogrow/fckplugin.js
===================================================================
--- editor/plugins/autogrow/fckplugin.js	(revision 962)
+++ editor/plugins/autogrow/fckplugin.js	(working copy)
@@ -63,6 +63,13 @@
 			return ;
 
 		window.frameElement.height = iMainFrameSize ;
+
+		// Gecko browsers use an onresize handler to update the innermost
+		// IFRAME's height. If the document is modified before the onresize
+		// is triggered, the plugin will miscalculate the new height. Thus,
+		// forcibly trigger onresize.
+		if ( typeof window.onresize === 'function' )
+			window.onresize() ;
 	}
 }