Add autodetect feature, effectively fixing #4 and #10

Checks if theres a battery menu, if not tries a11y, if all else fails it
resorts to using userMenu

presentationmode@ampad.de/extension.js

@@ -22,14 +22,30 @@ let SessionProxy = DBus.makeProxyClass(SessionIface);
 
 // Put your extension initialization code here
 function init(extensionMeta) {
+ // To Avoid issues and glitching, this needs to be placed here as
+ // batteryMenu must be constant after initialization to avoid
+ // problems with enable and disable functions
+
+ batteryMenu = Main.panel._statusArea.battery;
+ let temp = Main.panel._statusArea.battery._deviceItems;
+ if(temp == "")
+ {//check for no battery or power device, i.e. no power menu
+ lettemp = new Main.Panel.STANDARD_STATUS_AREA_SHELL_IMPLEMENTATION["a11y"]
+ if(Main.panel._statusArea.a11y != null)
+ {//check for no a11y (such as from noa11y extension)
+ batteryMenu = Main.panel._statusArea.a11y;
+ }
+ else
+ {//else use the user menu
+ batteryMenu = Main.panel._statusArea.userMenu;
+ }
+ }
  imports.gettext.bindtextdomain("gnome-shell-extension-presentationmode",
  extensionMeta.path + "/locale");
  imports.gettext.textdomain("gnome-shell-extension-presentationmode");
 }
 
 function enable() {
- let batteryMenu = Main.panel._statusArea.battery;
-
  batteryMenu._itemSeparator = new PopupMenu.PopupSeparatorMenuItem();
  batteryMenu.menu.addMenuItem(batteryMenu._itemSeparator);
  batteryMenu._presentationswitch = new PopupMenu.PopupSwitchMenuItem(_("Presentation mode"), false);
@@ -60,8 +76,6 @@ function enable() {
 }
 
 function disable() {
- let batteryMenu = Main.panel._statusArea.battery;
-
  batteryMenu._presentationswitch.destroy();
  batteryMenu._itemSeparator.destroy();
  if(batteryMenu._inhibit) {