disallow editing of password fields

common/content/editor.js

@@ -894,6 +894,13 @@ function Editor() //{{{
             if (!(config.isComposeWindow))
                 textBox = liberator.focus;
 
+			if (textBox.type == "password")
+			{
+                liberator.beep();
+			    liberator.echoerr("Cannot edit password fields");
+			    return false;
+			}
+
             let text = ""; // XXX
             if (textBox)
                 text = textBox.value;