Each plug-in contains a plugin.xml file defining how it interacts with the system. In order to extend the Eclipse Platform, extension definitions must be included in the plugin.xml file.

Extension points - There are many, many more.

• Applications - org.eclipse.core.runtime.applications
• Perspectives - org.eclipse.ui.perspectives
• Views - org.eclipse.ui.views
• ViewActions - org.eclipse.ui.viewActions
• Editors - org.eclipse.ui.editors
• EditorActions - org.eclipse.ui.editorActions
• PreferencePages - org.eclipse.ui.preferencePages

Plug-ins may also define their own extension points for other plug-ins (or even themselves!) to use.

Editors:
Only one instance of an editor can be open on an input (ie: only one editor that is currently editing readme.txt will ever be open). Input interface: org.eclipse.ui.IEditorInput

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Where can I get Javadoc for SWT?
A: The javadoc for SWT can be found in four places (note that all swt packages names begin with org.eclipse.swt):

1. http://download.eclipse.org/downloads/documentation/2.0/html/plugins/org.eclipse.platform.doc.isv/reference/api/
2. In Eclipse, under Help > Help Contents, Platform Plug-in Developer Guide > Reference > API Reference > Workbench
3. In the Eclipse installation: <eclipseRoot>/plugins/org.eclipse.platform.doc.isv_2.1.0/doc.zip
4. For the most up-to-date Javadoc, please read the code comments. The Windows version is always current; comments on other platforms are copied over right before a release.