InitScreen does not work well with fullscreen

Possible solution: use a different image (a 640x480px one) when fullscreen mode is selected.

Note: do not close issue until documented at https://github.com/asrob-uc3m/robotDevastation-user-manual

Start by locating the InitScreen entry point and checking how it selects or displays its image when fullscreen is enabled. Verify the fullscreen presentation with the proposed 640x480px image, then document the behavior or solution at the linked robotDevastation-user-manual before closing the issue.

Written by the indexing model from the issue text.