9 Advanced topics 9.1 VBoxSDL, the simplified VM displayer 9.1.1 Introduction VBoxSDL is a simple graphical user interface (GUI) that lacks the nice point-and-click support which VirtualBox, our main GUI, provides. VBoxSDL is currently primarily used internally for debugging VirtualBox and therefore not officially supported. Still, you may find it useful for environments where the virtual machines are not necessarily controlled by the same person that uses the virtual machine. Note: VBoxSDL is not available on the Mac OS X host platform. As you can see in the following screenshot, VBoxSDL does indeed only provide a simple win- dow that contains only the “pure” virtual machine, without menus or other controls to click upon and no additional indicators of virtual machine activity: To start a virtual machine with VBoxSDL instead of the VirtualBox GUI, enter the following on a command line: VBoxSDL --startvm vm where vm is, as usual with VirtualBox command line parameters, the name or UUID of an existing virtual machine. 9.1.2 Secure labeling with VBoxSDL When running guest operating systems in fullscreen mode, the guest operating system usually has control over the whole screen. This could present a security risk as the guest operating 134