disable input field when disconnected

www/contacts/main.js

@@ -39,12 +39,12 @@ define([
         toolbar.$rightside.html(''); // Remove the drawer if we don't use it to hide the toolbar
 
         Cryptpad.getProxy().on('disconnect', function () {
-            // TODO readonly
             Cryptpad.alert(Messages.common_connectionLost, undefined, true);
+            Cryptpad.enableMessaging(false);
         });
         Cryptpad.getProxy().on('reconnect', function () {
-            // TODO cancel readonly
             Cryptpad.findOKButton().click();
+            Cryptpad.enableMessaging(true);
         });
 
         Cryptpad.initMessaging(Cryptpad, $list, $messages);

www/contacts/main.less

@@ -223,7 +223,10 @@ body {
             resize: none;
             line-height: 50px;
             overflow-y: auto;
-            .placeholder;
+            .placeholder(#bbb);
+            &[disabled=true] {
+                .placeholder(#999);
+            }
             &:placeholder-shown { line-height: 50px; }
         }
         button {