Bug 55884 Loading a user library from file does not warn when overwriting an existing library [build path]
Works in I2004032400010 + plug-in export for I200403240800 Add library 'mylib'. Save it. Change it. Load library from file. ==> should warn that 'mylib' gets changed.
org.eclipse.jdt.ui/ui/org/eclipse/jdt/internal/ui/preferences/UserLibraryPreferencePage.java
/*
	 * (non-Javadoc)
	 * @see org.eclipse.jface.dialogs.IDialogPage#createControl(org.eclipse.swt.widgets.Composite)
	 */
	public void createControl(Composite parent) {
		super.createControl(parent);
		WorkbenchHelp.setHelp(getControl(), IJavaHelpContextIds.CP_USERLIBRARIES_PREFERENCE_PAGE);
	}	
	/*
	 * @see PreferencePage#createContents(org.eclipse.swt.widgets.Composite)
	 */
	protected Control createContents(Composite parent) {
		Composite composite= new Composite(parent, SWT.NONE);
		LayoutUtil.doDefaultLayout(composite, new DialogField[] { fLibraryList }, true);
		LayoutUtil.setHorizontalGrabbing(fLibraryList.getTreeControl(null));
		Dialog.applyDialogFont(composite);
		return composite;
	}
	
	/*
	 * @see IWorkbenchPreferencePage#init(org.eclipse.ui.IWorkbench)
	 */
	public void init(IWorkbench workbench) {
	}
	
	/*
	 * @see PreferencePage#performDefaults()
	 */
	protected void performDefaults() {
		super.performDefaults();