QuartzComposer CustomThumbnails
From VidvoxWiki
Embedding a custom thumbnail for a Quartz Composer patch.
1) Choose the Editor > Edit Information menu option
2) Click the + button to create a new row and set its class to the <data>
3) Navigate to the image file you want to use as a thumbnail.
4) Set the property key to "thumbnail" (no quotes)
The next time you load the patch as a source document in a VDMX media bin the new custom thumbnail will be used.
As a note, during file loading VDMX will automatically scale down the embedded image to 80x60 pixels making this is the ideal resolution to use for the images. Anything larger would only increase both the byte size of the QC patch and the amount of time needed to load the patch.