Cleanup: Fix freeze on Windows machines when running TaskVisualizer for a second time

Signed-off-by: Lukas Krawczyk <lukas.krawczyk@fh-dortmund.de>
diff --git a/plugins/org.eclipse.app4mc.multicore.execution.ui.simmenu/src/org/eclipse/app4mc/multicore/execution/ui/simmenu/handlers/SimMenuHandler.java b/plugins/org.eclipse.app4mc.multicore.execution.ui.simmenu/src/org/eclipse/app4mc/multicore/execution/ui/simmenu/handlers/SimMenuHandler.java
index 6c635de..8ca6d59 100644
--- a/plugins/org.eclipse.app4mc.multicore.execution.ui.simmenu/src/org/eclipse/app4mc/multicore/execution/ui/simmenu/handlers/SimMenuHandler.java
+++ b/plugins/org.eclipse.app4mc.multicore.execution.ui.simmenu/src/org/eclipse/app4mc/multicore/execution/ui/simmenu/handlers/SimMenuHandler.java
@@ -13,8 +13,6 @@
 
 package org.eclipse.app4mc.multicore.execution.ui.simmenu.handlers;
 
-import javax.swing.JOptionPane;
-
 import org.eclipse.app4mc.amalthea.model.ConstraintsModel;
 import org.eclipse.app4mc.amalthea.model.MappingModel;
 import org.eclipse.app4mc.multicore.execution.logic.openmapping.OMMapping;
@@ -72,9 +70,8 @@
 
 	private void showWizard(final Shell shell, final String path) {
 		if (this.tw.getFinish()) {
-			JOptionPane.showMessageDialog(null, "Please close the TraceView Tab before you start a new run", "Error",
-					JOptionPane.ERROR_MESSAGE);
-
+			MessageDialog.openInformation(shell, "Multiple Simulations not Supported",
+					"Please close the TraceView Tab before you start a new run.");
 			return;
 		}
 		final WizardDialog wizardDialog = new WizardDialog(shell,
@@ -88,7 +85,6 @@
 		}
 	}
 
-
 	private boolean readModels(final IFile file) {
 		if (file == null) {
 			return false;