Menu Button and Start Button
The Menu button and Start buttons are two standard Microsoft buttons. They are used respectively to show a context or the start menu.
The keyboard driver will need to post the following:
VK_LWIN virtual key message when the START button is pressed.
VK_APPS virtual key message when the MENU button is pressed.
Note that not all Windows Mobile devices support the MENU button, especially devices with 9–key keyboards.