Bug 41927 [Dialogs] Selecting in PreferenceDialog generates too many invalid entries
20030825 If you select an entry, close the dialog and then reopen it selecting anotehr entry will result in a "this page has invalid values" although you selected nothing.
bundles/org.eclipse.jface/src/org/eclipse/jface/preference/PreferenceDialog.java
* The default implementation of this framework method
	 * calls <code>performHelp</code> on the currently active page.
	 * </p>
	 */
	protected void helpPressed() {
		if (currentPage != null) {
			currentPage.performHelp();
		}
	}
	/**
	 * Returns whether the current page is valid.
	 *
	 * @return <code>false</code> if the current page is not valid, or
	 *  or <code>true</code> if the current page is valid or there is
	 *  no current page
	*/
	protected boolean isCurrentPageValid() {
		if (currentPage == null)
			return true;
		else
			return currentPage.isValid();
	}
	/**
	 * The preference dialog implementation of this <code>Dialog</code>
	 * framework method sends <code>performOk</code> to all pages of the 
	 * preference dialog, then calls <code>handleSave</code> on this dialog
	 * to save any state, and then calls <code>close</code> to close
	 * this dialog.
	 */
	protected void okPressed() {