content: package com.japisoft.xmlpad.action.edit;
  
  import com.japisoft.xmlpad.action.XMLAction;
  
  /**
  This program is available under two licenses : 
  
  1. For non commercial usage : 
  
  This program is free software: you can redistribute it and/or modify
  it under the terms of the GNU General Public License as published by
  the Free Software Foundation, either version 3 of the License, or
  (at your option) any later version.
  
  This program is distributed in the hope that it will be useful,
  but WITHOUT ANY WARRANTY; without even the implied warranty of
  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  GNU General Public License for more details.
  
  You should have received a copy of the GNU General Public License
  along with this program.  If not, see <http://www.gnu.org/licenses/>.
  
  2. For commercial usage :
  
  You need to get a commercial license for source usage at : 
  
  http://www.editix.com/buy.html
  
  Copyright (c) 2018 Alexandre Brillant - JAPISOFT SARL - http://www.japisoft.com
  
  @author Alexandre Brillant - abrillant@japisoft.com
  @author JAPISOFT SARL - http://www.japisoft.com
  
  */
  public class UndoAction extends XMLAction  {
  
  	public static final String ID = UndoAction.class.getName();
  	
  	public UndoAction() {
  		super();
  	}
  
  	public boolean notifyAction() {
  		editor.undo();
  		return VALID_ACTION;
  	}
  
  	protected boolean autoRequestFocus() { return false; }
  
  	protected void notifyXMLContainer() {
  		try {
  			Boolean previousState = ( Boolean )container.getProperty( "state.undo" );
  			if ( previousState != null ) {
  				setEnabled( previousState.booleanValue() );
  				return;
  			}
  
  			setEnabled( 
  				container.isEditable() && 
  					container.getEditor().getUndoManager().canUndo() );
  
  		} catch( NullPointerException ex ) {
  			// ??
  			setEnabled( false );
  		}
  	}
  
  }
  
  // NewAction ends here
  