show crosshair cursor when alt is pressed

lib/ace/multi_select.js

@@ -623,6 +623,33 @@ function MultiSelect(editor) {
 
     editor.on("mousedown", onMouseDown);
     editor.commands.addCommands(exports.commands.defaultCommands);
+    
+    addAltCursorListeners(editor);
+}
+
+function addAltCursorListeners(editor){
+    var el = editor.textInput.getElement();
+    var altCursor = false;
+    var contentEl = editor.renderer.content;
+    el.addEventListener("keydown", function(e) {
+        if (e.keyCode == 18 && !(e.ctrlKey || e.shiftKey || e.metaKey)) {
+            if (!altCursor) {
+                contentEl.style.cursor = "crosshair";
+                altCursor = true;
+            }
+        } else if (altCursor) {
+            contentEl.style.cursor = "";
+        }
+    });
+    
+    el.addEventListener("keyup", reset);
+    el.addEventListener("blur", reset);
+    function reset() {
+        if (altCursor) {
+            contentEl.style.cursor = "";
+            altCursor = false;
+        }
+    }
 }
 
 exports.MultiSelect = MultiSelect;