Bug 332930 Simplify code from bug 207510
There is a listener added to ProjectPreferences that will never be removed. Try to simplify the code to get rid of this listener.
bundles/org.eclipse.ui.ide/src/org/eclipse/ui/ide/dialogs/ResourceEncodingFieldEditor.java
AbstractEncodingFieldEditor {
	/**
	 * The resource being edited.
	 */
	private IResource resource;
	private Composite group;
	private Button separateDerivedEncodingsButton = null;
	/**
	 * Creates a new encoding field editor for setting the encoding on the given
	 * resource.
	 * 
	 * @param labelText
	 *            the label text of the field editor
	 * @param parent
	 *            the parent of the field editor's control
	 * @param charsetResource
	 *            must be an <code>IContainer</code> or an <code>IFile</code>.