Bug 37155 [Preferences] StringButtonFieldEditor should disable button when disabled.
setEnabled() should not only enable/disable the text string, it should also enable/disable the button, or should provide the capability for enabling/disabling the button separately. This problem is most evident when using a DirectoryFieldEditor. After disabling it, the user can still press on the "Browse..." button.
bundles/org.eclipse.jface/src/org/eclipse/jface/preference/StringButtonFieldEditor.java
/**
	 * The change button, or <code>null</code> if none
	 * (before creation and after disposal).
	 */
	private Button changeButton;
	
	/**
	 * The text for the change button, or <code>null</code> if missing.
	 */
	private String changeButtonText;
/**
 * Creates a new string button field editor 
 */
protected StringButtonFieldEditor() {
}
/**
 * Creates a string button field editor.
 * 
 * @param name the name of the preference this field editor works on
 * @param labelText the label text of the field editor
 * @param parent the parent of the field editor's control
 */
protected StringButtonFieldEditor(String name, String labelText, Composite parent) {
	init(name, labelText);