Mindcraft Max posted that you could use a number reference instead of the icon from the gallery, and also posted some kode that gave you the icons image number. I have no idea what practical use this might have in Project Spark but some of you may find this interesting.
To display an icon using its number
WHEN DO [display] [txt: [image:14970308214818915828] ][screen bottom center] // this displays the 0-1 icon as an example
To find any icon’s number
WHEN DO [txt var: icon] [equals] [txt: <][icon: your choice]
WHEN DO [display] [icon][screen bottom center] //will display the icon number