added basic tool tip for testing

bigbluebutton-html5/imports/ui/components/nav-bar/component.jsx

@@ -70,15 +70,18 @@ class NavBar extends Component {
     return (
       <div className={styles.navbar}>
         <div className={styles.left}>
-          <Button
-            onClick={this.handleToggleUserList}
-            ghost={true}
-            circle={true}
-            hideLabel={true}
-            label={'Toggle User-List'}
-            icon={'user'}
-            className={cx(toggleBtnClasses)}
-          />
+          <div className={styles.tooltip}>
+            <Button
+              onClick={this.handleToggleUserList}
+              ghost={true}
+              circle={true}
+              hideLabel={true}
+              label={'Toggle User-List'}
+              icon={'user'}
+              className={cx(toggleBtnClasses)}
+            />
+            <span className={styles.tooltiptext}>text here</span>
+          </div>
         </div>
         <div className={styles.center}>
           {this.renderPresentationTitle()}

bigbluebutton-html5/imports/ui/components/nav-bar/styles.scss

@@ -87,3 +87,27 @@
 .dropdownBreakout {
   cursor: pointer;
 }
+
+
+.tooltip {
+    position: relative;
+    display: inline-block;
+}
+
+.tooltip .tooltiptext {
+    visibility: hidden;
+    width: 120px;
+    background-color: black;
+    color: #fff;
+    text-align: center;
+    border-radius: 6px;
+    padding: 5px 0;
+
+    /* Position the tooltip */
+    position: absolute;
+    z-index: 1;
+}
+
+.tooltip:hover .tooltiptext {
+    visibility: visible;
+}