Exception on Visualization Settings if opened before Overview

[Mathieu Bastian]

Way to reproduce:
1) Close Gepgi from the Data Laboratory tab
2) Open Gephi
3) Tools > Options > Visualization

Stack Trace:
java.lang.NullPointerException
 at org.gephi.visualization.options.OpenGLPanel.load(OpenGLPanel.java:490)
 at org.gephi.visualization.options.OpenGLOptionsPanelController.update(OpenGLOptionsPanelController.java:37)
 at org.netbeans.modules.options.TabbedController.handleTabSwitched(TabbedController.java:214)
 at org.netbeans.modules.options.TabbedController.access$200(TabbedController.java:79)
 at org.netbeans.modules.options.TabbedController$2.stateChanged(TabbedController.java:106)
 at javax.swing.JTabbedPane.fireStateChanged(JTabbedPane.java:400)
 at javax.swing.JTabbedPane$ModelListener.stateChanged(JTabbedPane.java:253)
 at javax.swing.DefaultSingleSelectionModel.fireStateChanged(DefaultSingleSelectionModel.java:116)
 at javax.swing.DefaultSingleSelectionModel.setSelectedIndex(DefaultSingleSelectionModel.java:50)
 at javax.swing.JTabbedPane.setSelectedIndexImpl(JTabbedPane.java:599)
 at javax.swing.JTabbedPane.setSelectedIndex(JTabbedPane.java:574)
 at javax.swing.plaf.basic.BasicTabbedPaneUI$Handler.mousePressed(BasicTabbedPaneUI.java:3606)
 at java.awt.Component.processMouseEvent(Component.java:6038)