Just to share a small addon to manage alpha blending I made with Roassal. 

Try in an easel the following:

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random := Random new.
view shape circle size: 80; fillColor: Color black. 
view interaction on: ROMouseEnter do: [ :event |
ROColorAlphaFading new for: event element nbCycles: 60 ].
nodes := view nodes: (1 to: 50). 
nodes do: [:el | el translateTo: (random next * 400) @ (random next * 400) ].
view noLayout.

ROPluggableAnimation new
nbCycles: 20000;
block: [ ROColorAlphaFading new for: nodes atRandom nbCycles: 60 ];
on: view raw.
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view shape circle size: 80; fillColor: Color black. 

view interaction on: ROMouseEnter do: [ :event |
ROColorAlphaFading new for: event element nbCycles: 60 ].
view nodes: (1 to: 50).
view gridLayout.
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It also works with edges:
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view interaction 
dynamicEdgeToAll: [ :model | (1 to: model) collect: [ :v | v // 2 ] ]
usingFading: (ROLine red width: 5; attachPoint: ROCenteredAttachPoint instance).

view shape rectangle size: 20.
view nodes: (1 to: 20).
 
view circleLayout.