diff -r 639eb3617a86 -r 6338355b2a88 src/Tools/VSCode/extension/package.json
--- a/src/Tools/VSCode/extension/package.json	Mon May 29 09:14:15 2017 +0200
+++ b/src/Tools/VSCode/extension/package.json	Mon May 29 15:16:32 2017 +0200
@@ -22,6 +22,12 @@
     ],
     "main": "./out/src/extension",
     "contributes": {
+        "commands": [
+            {
+                "command": "isabelle.preview",
+                "title": "Isabelle Document Preview"
+            }
+        ],
         "languages": [
             {
                 "id": "isabelle",