Reason/background: I use a universal remote, and the volume keys including the mute key are programmed to change the AVR volume, so they don't reach the STB at all. Arguably these keys are not the most intuitive keys to change the videotext modes anyway.
What it does: The patch makes KEY_PREVIOUS behave like KEY_VOLUMEUP, KEY_NEXT like KEY_VOLUMEDOWN, and KEY_TEXT like KEY_MUTE