Ksp reference Manual

Instrument Icon and Wallpaper
$INST_ICON_ID
The (fixed) ID of the instrument icon.
It's possible to hide the instrument icon:
set_control_par($INST_ICON_ID,$CONTROL_PAR_HIDE,$HIDE_WHOLE_CONTROL)
It's also possible to load a different picture file for the instrument icon:
set_control_par_str($INST_ICON_ID,$CONTROL_PAR_PICTURE,)
$INST_WALLPAPER_ID
The (fixed) ID of the instrument wallpaper. It is used in a similar way as 
$INST_ICON_ID
:
set_control_par_str ($INST_WALLPAPER_ID,$CONTROL_PAR_PICTURE,)
This command can only be used in the init callback. Note that a wallpaper set via script replaces the one set in the instrument
options and it will not be checked in the samples missing dialog when loading the wallpaper from a resource container.
This command only supports wallpapers that are located within the resource container.
If you use it in different script slots then the last wallpaper set will be the one that is loaded.