how about if when the pixel particles moved towards gravity (also being affected by pressure) and they were all moving together at the same speed. if any of the partivcles in the group touched something else (i.e. metal and dust then they will stop and move to the left or right(dpending on which one is closer to the source of gravity or low pressure.
p.s. sorry for the bad spelling, no time.
p.p.s. and my brother suggested glue.
It's good and all that you guys want to help with TPT. HOWEVER. Doing what you are doing right now is the equivalent of going to a volunteering organisation, without being a volunteer yourself, and make dictate how _they_ should do things that they do out of free will. It's almost rude and makes you look stupid to be honest.
i may have a solution to he moving solids problem... keyword MAY, OE-cake... but it's probably incompatible and would require a full rewrite or something... just thought i'd mention it. i can't find an official website, so just google OE-cake.