Re: How to retrieve a certain project component instance given a project instance?

You can get a project component instance using project.getComponent(YourProjectComponent.class) call. To obtain a 'project' instance inside an action
you can use AnActionEvent#getProject method (also we have ProjectManager#getOpenProjects() method but usually you don't need this).

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Nikolay Chashnikov
JetBrains
http://www.jetbrains.com
"Develop with pleasure!"