public void run() {
                	String error = "The tileserver \"" + getTileServer().getURL() + "\" could not be reached.\r\nMaybe configuring a http-proxy is required.";
                    JOptionPane.showMessageDialog(
                            SwingUtilities.getWindowAncestor(MapPanel.this),
                            error, "TileServer not reachable.", JOptionPane.ERROR_MESSAGE);
                }