public void propertyChange(PropertyChangeEvent ev) {

			Program program = this.controller.get().program;
			if (program == null) {
				((UserPreferences) ev.getSource())
						.removePropertyChangeListener("language", this);
			} else {
				program.getTabbedPane().setTitleAt(0,
						Tools.getLocalizedString("PROJECT"));
				if(program.getMainPanel().getxHTMLPanel().getDocumentTitle().equals("Welcome Page")){
					try {
						program.getMainPanel().getxHTMLPanel().setDocument(new File(Tools
								.getLocalizedString("WELCOME_PAGE")));
					} catch (Exception e) {
						e.printStackTrace();
					}
				}
				else{
					if(program.getMainPanel().getTextField().getText()
						.compareTo("") != 0)
					if (program.getUserPreferences().getSolutionType()
							.compareTo(SolutionType.DETAILLED_SOLUTION) == 0)
						program.getController().simplify(
								SolutionType.DETAILLED_SOLUTION);
					else
						program.getController().simplify(
								SolutionType.MINIMIZED_FUNCTION);
				program.getMainPanel().lblF.setText(Tools
						.getLocalizedString("FORMULA"));
				}
			}
		}