add anchor demo

demo/demo.js

@@ -126,6 +126,27 @@ exports.launch = function(env) {
     var container = document.getElementById("editor");
     env.editor = new Editor(new Renderer(container, theme));
 
+    var Anchor = require("ace/anchor").Anchor;
+    var Range = require("ace/range").Range;
+    
+    var anchorStart = new Anchor(docs.js, 2, 8);
+    var anchorEnd = new Anchor(docs.js, 2, 13);
+
+    var marker;
+    function updateFloat() {
+        if (marker)
+            env.editor.renderer.removeMarker(marker);
+        var range = Range.fromPoints(
+            anchorStart.getPosition(),
+            anchorEnd.getPosition()
+        );
+        console.log(range);
+        marker = env.editor.renderer.addMarker(range, "cool", "text");
+    };
+    updateFloat();
+    anchorStart.on("change", updateFloat);
+    anchorEnd.on("change", updateFloat);
+
     var modes = {
         text: new TextMode(),
         xml: new XmlMode(),

demo/styles.css

@@ -15,6 +15,12 @@ body {
     color: white;
 }
 
+#editor .cool {
+    position: absolute;
+    z-index: 4;
+    background: orange;
+}
+
 #editor {
     position: absolute;
     top: 60px;