Index: trunk/de.ugoe.cs.swe.exercises/META-INF/MANIFEST.MF
===================================================================
--- trunk/de.ugoe.cs.swe.exercises/META-INF/MANIFEST.MF	(revision 7)
+++ trunk/de.ugoe.cs.swe.exercises/META-INF/MANIFEST.MF	(revision 8)
@@ -10,5 +10,6 @@
  net.sourceforge.texlipse;bundle-version="1.3.0",
  org.eclipse.core.filesystem;bundle-version="1.2.0",
- org.eclipse.ui.ide;bundle-version="3.5.1"
+ org.eclipse.ui.ide;bundle-version="3.5.1",
+ org.eclipse.core.resources;bundle-version="3.5.1"
 Bundle-ActivationPolicy: lazy
 Bundle-RequiredExecutionEnvironment: JavaSE-1.6
Index: trunk/de.ugoe.cs.swe.exercises/src/de/ugoe/cs/swe/exercises/exercisesheet/ExerciseSheetComposite.java
===================================================================
--- trunk/de.ugoe.cs.swe.exercises/src/de/ugoe/cs/swe/exercises/exercisesheet/ExerciseSheetComposite.java	(revision 7)
+++ trunk/de.ugoe.cs.swe.exercises/src/de/ugoe/cs/swe/exercises/exercisesheet/ExerciseSheetComposite.java	(revision 8)
@@ -1,26 +1,11 @@
 package de.ugoe.cs.swe.exercises.exercisesheet;
 
-import java.awt.Desktop;
 import java.io.File;
-import java.io.IOException;
 import java.util.ArrayList;
-import org.eclipse.swt.widgets.Composite;
-import org.eclipse.swt.widgets.FileDialog;
-import org.eclipse.swt.widgets.Shell;
-import org.eclipse.swt.widgets.TableItem;
-import org.eclipse.swt.widgets.Text;
-import org.eclipse.swt.layout.GridData;
-import org.eclipse.swt.layout.GridLayout;
-import org.eclipse.swt.widgets.Button;
+
+import org.eclipse.core.filesystem.EFS;
+import org.eclipse.core.filesystem.IFileStore;
 import org.eclipse.swt.SWT;
-import org.eclipse.swt.widgets.Label;
-import de.ugoe.cs.swe.exercises.exercise.Exercise;
-import de.ugoe.cs.swe.exercises.exercise.ExerciseSVN;
-import de.ugoe.cs.swe.exercises.lecture.GUITreeView;
-import de.ugoe.cs.swe.exercises.misc.CKeyword;
-import de.ugoe.cs.swe.exercises.misc.KeywordsCompositeExtender;
-
-import org.eclipse.swt.widgets.Table;
-import org.eclipse.swt.widgets.TableColumn;
+import org.eclipse.swt.custom.SashForm;
 import org.eclipse.swt.dnd.DND;
 import org.eclipse.swt.dnd.DragSource;
@@ -32,10 +17,32 @@
 import org.eclipse.swt.dnd.TextTransfer;
 import org.eclipse.swt.dnd.Transfer;
+import org.eclipse.swt.events.ModifyEvent;
 import org.eclipse.swt.events.ModifyListener;
-import org.eclipse.swt.events.ModifyEvent;
 import org.eclipse.swt.events.SelectionAdapter;
 import org.eclipse.swt.events.SelectionEvent;
+import org.eclipse.swt.layout.GridData;
+import org.eclipse.swt.layout.GridLayout;
+import org.eclipse.swt.widgets.Button;
+import org.eclipse.swt.widgets.Composite;
+import org.eclipse.swt.widgets.FileDialog;
 import org.eclipse.swt.widgets.Group;
-import org.eclipse.swt.custom.SashForm;
+import org.eclipse.swt.widgets.Label;
+import org.eclipse.swt.widgets.Shell;
+import org.eclipse.swt.widgets.Table;
+import org.eclipse.swt.widgets.TableColumn;
+import org.eclipse.swt.widgets.TableItem;
+import org.eclipse.swt.widgets.Text;
+import org.eclipse.ui.IEditorInput;
+import org.eclipse.ui.IEditorRegistry;
+import org.eclipse.ui.IWorkbenchPage;
+import org.eclipse.ui.PartInitException;
+import org.eclipse.ui.PlatformUI;
+import org.eclipse.ui.ide.FileStoreEditorInput;
+
+import de.ugoe.cs.swe.exercises.exercise.Exercise;
+import de.ugoe.cs.swe.exercises.exercise.ExerciseSVN;
+import de.ugoe.cs.swe.exercises.lecture.GUITreeView;
+import de.ugoe.cs.swe.exercises.misc.CKeyword;
+import de.ugoe.cs.swe.exercises.misc.KeywordsCompositeExtender;
 
 public class ExerciseSheetComposite extends Composite {
@@ -311,13 +318,20 @@
 						.getProperty("java.io.tmpdir")
 						+ "/tempPDFfileForPreview.pdf", false, true);
+				File f = new File(System.getProperty("java.io.tmpdir")
+						+ "/tempPDFfileForPreview.pdf");
+
+				IWorkbenchPage activePage = PlatformUI.getWorkbench()
+						.getActiveWorkbenchWindow().getActivePage();
+
+				final IFileStore fileStore = EFS.getLocalFileSystem().getStore(
+						f.toURI());
+
+				IEditorInput editorInput = new FileStoreEditorInput(fileStore);
 				try {
-					Desktop d = Desktop.getDesktop();
-					d.open(new File(System.getProperty("java.io.tmpdir")
-							+ "/tempPDFfileForPreview.pdf"));
-
-				} catch (IOException e1) {
-					System.err.println(e1);
+					activePage.openEditor(editorInput,
+							IEditorRegistry.SYSTEM_EXTERNAL_EDITOR_ID);
+				} catch (PartInitException e1) {
+					e1.printStackTrace();
 				}
-
 			}
 		});
Index: trunk/de.ugoe.cs.swe.exercises/src/de/ugoe/cs/swe/exercises/exercisesheet/ExerciseSheetPDFDialog.java
===================================================================
--- trunk/de.ugoe.cs.swe.exercises/src/de/ugoe/cs/swe/exercises/exercisesheet/ExerciseSheetPDFDialog.java	(revision 7)
+++ trunk/de.ugoe.cs.swe.exercises/src/de/ugoe/cs/swe/exercises/exercisesheet/ExerciseSheetPDFDialog.java	(revision 8)
@@ -1,4 +1,3 @@
 package de.ugoe.cs.swe.exercises.exercisesheet;
-
 
 import java.awt.Desktop;
@@ -6,5 +5,6 @@
 import java.io.IOException;
 
-
+import org.eclipse.core.filesystem.EFS;
+import org.eclipse.core.filesystem.IFileStore;
 import org.eclipse.jface.dialogs.IMessageProvider;
 import org.eclipse.jface.dialogs.TitleAreaDialog;
@@ -21,5 +21,10 @@
 import org.eclipse.swt.widgets.Label;
 import org.eclipse.swt.widgets.Shell;
-
+import org.eclipse.ui.IEditorInput;
+import org.eclipse.ui.IEditorRegistry;
+import org.eclipse.ui.IWorkbenchPage;
+import org.eclipse.ui.PartInitException;
+import org.eclipse.ui.PlatformUI;
+import org.eclipse.ui.ide.FileStoreEditorInput;
 
 public class ExerciseSheetPDFDialog extends TitleAreaDialog {
@@ -36,5 +41,5 @@
 		super(parentShell);
 		super.setShellStyle(0);
-		if(!file.endsWith(".pdf"))
+		if (!file.endsWith(".pdf"))
 			file += ".pdf";
 		ExerciseSheetPDFDialog.fileName = file;
@@ -87,16 +92,23 @@
 		button.setLayoutData(buttonlayout);
 		button.addSelectionListener(new SelectionAdapter() {
-			
 
 			@Override
 			public void widgetSelected(SelectionEvent e) {
+				IWorkbenchPage activePage = PlatformUI.getWorkbench()
+						.getActiveWorkbenchWindow().getActivePage();
 
+				File f = new File(ExerciseSheetPDFDialog.fileName);
+
+				final IFileStore fileStore = EFS.getLocalFileSystem().getStore(
+						f.toURI());
+
+				IEditorInput editorInput = new FileStoreEditorInput(fileStore);
 				try {
-					Desktop d = Desktop.getDesktop();
-					d.open(new File(ExerciseSheetPDFDialog.fileName));
-				} catch (IOException e1) {
-					// TODO Auto-generated catch block
-					System.err.println(e1);
+					activePage.openEditor(editorInput,
+							IEditorRegistry.SYSTEM_EXTERNAL_EDITOR_ID);
+				} catch (PartInitException e1) {
+					e1.printStackTrace();
 				}
+
 				shell.setEnabled(true);
 				close();