GUACAMOLE-567: Warn user when tunnel enters "UNSTABLE" state.

guacamole/src/main/webapp/app/client/styles/connection-warning.css

@@ -0,0 +1,36 @@
+/*
+ * Licensed to the Apache Software Foundation (ASF) under one
+ * or more contributor license agreements.  See the NOTICE file
+ * distributed with this work for additional information
+ * regarding copyright ownership.  The ASF licenses this file
+ * to you under the Apache License, Version 2.0 (the
+ * "License"); you may not use this file except in compliance
+ * with the License.  You may obtain a copy of the License at
+ *
+ *   http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing,
+ * software distributed under the License is distributed on an
+ * "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
+ * KIND, either express or implied.  See the License for the
+ * specific language governing permissions and limitations
+ * under the License.
+ */
+
+#connection-warning {
+
+    position: absolute;
+    right: 0.25em;
+    top: 0.25em;
+    z-index: 20;
+
+    max-width: 100%;
+    max-height: 3in;
+
+    border: 1px solid rgba(0,0,0,0.5);
+    box-shadow: 1px 1px 2px rgba(0,0,0,0.25);
+    background: #FFE;
+    padding: 0.5em;
+    font-size: .8em;
+
+}