Release 5.2
diff --git a/src/js/shortcut.js b/src/js/shortcut.js
new file mode 100644
index 0000000..7959178
--- /dev/null
+++ b/src/js/shortcut.js
@@ -0,0 +1,35 @@
+var shortcutKey = {

+

+  init: function() {

+    if (document.body.hasAttribute('screen_capture_injected')) {

+      return;

+    }

+    document.body.setAttribute('screen_capture_injected', true);

+    document.body.addEventListener('keydown', shortcutKey.handleShortcut,

+      false);

+  },

+

+  isThisPlatform: function(operationSystem) {

+    return navigator.userAgent.toLowerCase().indexOf(operationSystem) > -1;

+  },

+

+  handleShortcut: function (event) {

+    var isMac = shortcutKey.isThisPlatform('mac');

+    var keyCode = event.keyCode;

+    // Send compose key like Ctrl + Alt + alphabetical-key to background.

+    if ((event.ctrlKey && event.altKey && !isMac ||

+          event.metaKey && event.altKey && isMac) &&

+        keyCode > 64 && keyCode < 91) {

+      shortcutKey.sendMessage({

+        msg: 'capture_hot_key',

+        keyCode: keyCode

+      });

+    }

+  },

+

+  sendMessage: function(message) {

+    chrome.extension.sendMessage(message);

+  }

+};

+

+shortcutKey.init();