Bug 85147 [Preferences] filter field: Looses focus on type
20050208 When you type in the filter field, the focus ofter switched to the tree. You have to give the filter field the focus again to continue typing
bundles/org.eclipse.jface/src/org/eclipse/jface/preference/PreferenceDialog.java
*/
	public void setErrorMessage(String newErrorMessage) {
		if (newErrorMessage == null)
			messageArea.clearErrorMessage();
		else
			messageArea.updateText(newErrorMessage, IMessageProvider.ERROR);
	}
	/**
	 * Save the last known tree width.
	 * 
	 * @param width
	 *            the width.
	 */
	private void setLastTreeWidth(int width) {
		lastTreeWidth = width;
	}
	/**
	 * Sets whether a Help button is available for this dialog.
	 * <p>
	 * Clients must call this framework method before the dialog's control has
	 * been created.
	 * <p>
	 * 
	 * @param b
	 *            <code>true</code> to include a Help button, and
	 *            <code>false</code> to not include one (the default)
	 */
	public void setHelpAvailable(boolean b) {
		isHelpAvailable = b;
	}