some fixes; asynchronous message decryption to keep browser responsive

nodejs/public/stylesheets/safechat.css

@@ -188,6 +188,11 @@ td:last-child {
 .clear {
   clear: both;
 }
+:disabled {
+  opacity: 0.4;
+  filter: alpha(opacity=40); /* MSIE */
+  background-color: lightgray;
+}
 label[for=send] img {
   opacity: 0.4;
   filter: alpha(opacity=40); /* MSIE */