I'm working with the particle editor in PD13 and there's a behaviour that I don't understand. I use a standard with PD13 supplied particle (Facebook like thumb) and I get this result:



The thing I don't understand are the vague thumbs that appear to the right of the screen (marked with the grey arrows). What setting in the particle editor makes them appear over there? I tried every setting but I can't figure it out.

These are the current settings:
Emit method: Point
Emit rate: 5000
Max count: 500
Life: 3200
Size: 6800
Speed: 4000

All other settings are 0. I hope you can help me out!