如何在Eclipse 4 RCP中将Part插入另一个插件的PartStack？

I'd like to practice Eclipse 4 RCP application development, and my current goal is a graph modeling application. As far as I know GEF (Graphical Editing Framework) is the most reliable graphical framework, but it is Eclipse 3.x only. So I decided to create a plug-in only for the editor but I don't know how to insert the graphical editor's Part into the main plug-in's Application Model. What's more, how two plug-ins can communicate with each other?I'd like to practice Eclipse 4 RCP application