If VBox SDL is unable to choose a higher resolution, the secure label will be painted on top of the guest's screen surface.
In order to address the problem of the bottom part of the guest screen being hidden, VBox SDL can provide custom video modes to the guest that are reduced by the height of the label.
For Windows guests and recent Solaris and Linux guests, the Virtual Box Guest Additions automatically provide the reduced video modes.
VBox SDL is a simple graphical user interface (GUI) that lacks the nice point-and-click support which Virtual Box, our main GUI, provides.
VBox SDL is currently primarily used internally for debugging Virtual Box and therefore not officially supported.