Provides a set of classes that implement a `Service` that facilitates the contribution of actions to modeling platform workbench parts. It is meant to address some of the deficiencies in the Eclipse support for static action contributions, as follows:

- adds support for static contribution of custom contribution items
- adds support for static menu contributions to toolbar managers
- adds support for static contributions to menu managers that have been added programmatically to a toolbar
- adds support for complex action enablement and visibility criteria

In order to contribute contributions items to the service, clients should use the `org.eclipse.gmf.runtime.common.ui.services.action.contributionItemProviders` extension point. The provider implementation specified in the extension point should subclass the {@link org.eclipse.gmf.runtime.common.ui.services.action.contributionitem.AbstractContributionItemProvider} class in this package.

Contributions made through this extension point could be for a workbench part's action bars (referred to as part contributions) or for a workbench part's popup menu (referred to as popup contributions). The extension point provides an XML description of those contributions to be read by the described providers. The extension point provides an alternative to the following Eclipse extension points:

- org.eclipse.ui.editorActions
- org.eclipse.ui.viewActions
- org.eclipse.ui.popupMenus (viewerContribution)

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