I am currently using Sirius to create a graphical editor. I have three types of Diagrams: State Diagram, Feature Model and Feature Class diagrams. What I need to do is to use KIELER only for Feature Model diagram , and let Sirius default layout provider do layouting for the other State Diagram and Feature Class Diagrams.
Can I do it through some plugin extension points ?
The Sirius default layout provider is the same used by GMF, which is the layer-based algorithm provided by Draw2d, right? That one is also available in KIELER / ELK, so you could actually use ELK for all of your diagram types and then choose a different algorithm for each type using the ELK configuration infrastructure.
Actually, I need to completely disable KIELER and not using Draw2D algorithm option the reason is that, KIELER automatically resizes nodes when I do layouting  !!! I found that if I statically config and set BorderSpacing to zero (0), then it will be fixed and nodes will not be resized ! This works great only in one of the diagrams, and I'm OK with it, but for the two other diagram types it messes up with other parts, So I' thinking of just using KIELER for one of the diagram types and ignore using it for the other two diagram types.
You can control almost every aspect of the ELK layout through layout options. There's also an option for disabling automatic node resizing (id "org.eclipse.elk.nodeSize.options"). It's this flexibility why I would recommend to use ELK instead of the default layout provider.