gui: fix exception when using keyboard in the menus

java.lang.Error: Cannot call invokeAndWait from the event dispatcher
thread
Cannot call invokeAndWait from the event dispatcher thread
java.awt.EventQueue.invokeAndWait(EventQueue.java:1254)
java.awt.EventQueue.invokeAndWait(EventQueue.java:1247)
javax.swing.SwingUtilities.invokeAndWait(SwingUtilities.java:1346)
lcmc.utilities.Tools.invokeAndWait(Tools.java:2444)
lcmc.gui.dialog.ConfigDialog.showDialog(ConfigDialog.java:484)
lcmc.utilities.Tools.confirmDialog(Tools.java:253)
lcmc.gui.ClusterBrowser.hbDrbdConfirmDialog(ClusterBrowser.java:2160)
lcmc.gui.resources.ServicesInfo$13$4.action(ServicesInfo.java:1494)
lcmc.utilities.Tools$7.keyPressed(Tools.java:1575)
GUI: don't allow to enter the same cluster name

java.lang.NullPointerException
null
lcmc.gui.resources.AllHostsInfo$1.run(AllHostsInfo.java:149)
java.lang.Thread.run(Thread.java:724)
GUI: disallow to close cluster tabs during the cluster wizard
GUI: fix exception when starting/stopping hb/corosync

with hosts that are not defined to be in a cluster

java.lang.NullPointerException
null
lcmc.gui.resources.HostInfo$20.action(HostInfo.java:879)
lcmc.utilities.MyMenuItem$9.run(MyMenuItem.java:367)
java.lang.Thread.run(Unknown Source)