Index: /CKEditor/trunk/_source/plugins/pastefromword/dialogs/pastefromword.js
===================================================================
--- /CKEditor/trunk/_source/plugins/pastefromword/dialogs/pastefromword.js	(revision 3409)
+++ /CKEditor/trunk/_source/plugins/pastefromword/dialogs/pastefromword.js	(revision 3410)
@@ -139,4 +139,8 @@
 		onShow : function()
 		{
+			// FIREFOX BUG: Force the browser to render the dialog to make the to-be-
+			// inserted iframe editable. (#3366)
+			this.parts.dialog.$.offsetHeight;
+			
 			var container = this.getContentElement( 'general', 'editing_area' ).getElement(),
 				iframe = CKEDITOR.dom.element.createFromHtml( '<iframe src="javascript:void(0)" frameborder="0" allowtransparency="1"></iframe>' );