Q:

IDocument cannot be resolved to a type

I'm very new to eclipse plugin devalopment and i want to get content from editor using eclipse plugin so i found this answer.
But problem is: I get the compile error IDocument cannot be resolved to a type. No quick fix imports available. My Eclipse version is  3.8.2.
How can I fix this problem?
The code I used (from the linked answer) is this:
public String getCurrentEditorContent() {
    final IEditorPart activeEditor = PlatformUI.getWorkbench().getActiveWorkbenchWindow().getActivePage()
            .getActiveEditor();
    if (activeEditor == null)
        return null;
    final IDocument doc = (IDocument) activeEditor.getAdapter(IDocument.class);
    if (doc == null) return null;

    return doc.get();
}

I can't find org.eclipse.jface.text among my dependencies. Here is a snapshot:

A:

IDocument is in the org.eclipse.text plugin so you must add this to your plugin's dependencies list.
Note: You can also add the org.eclipse.jface.text plugin to the dependencies list as that will include the org.eclipse.text plugin.

