The following sample comes with Trados 2014 SDK shows how to add custom action to custom ribbon group.
Is there a way to add custom action to editor's context menu?
Please see attachment for details.
[Action("MyTopNormalSizeAction", typeof (StudioContext))]
[ActionLayout(typeof (MySampleRibbonGroup), 9, DisplayType.Normal)]
public class MyTopAction : AbstractControllerAction<EditorController>
{
protected override void Execute()
{
MessageBox.Show(string.Format("There are(is) {0} document(s) opened in the editor",
Controller.GetDocuments().Count()));
}
}