From c7c1f97b0c2a5f2da6957264a0c54a791cb8ebac Mon Sep 17 00:00:00 2001
From: Brita Keller <brita@minres.com>
Date: Wed, 18 Dec 2019 17:16:20 +0100
Subject: [PATCH] Fixed #21 - IllegalStateException when closing SCViewer

---
 .../scviewer/e4/application/parts/DesignBrowser.java  | 11 ++++++++---
 1 file changed, 8 insertions(+), 3 deletions(-)

diff --git a/com.minres.scviewer.e4.application/src/com/minres/scviewer/e4/application/parts/DesignBrowser.java b/com.minres.scviewer.e4.application/src/com/minres/scviewer/e4/application/parts/DesignBrowser.java
index 0de7795..f2444fa 100644
--- a/com.minres.scviewer.e4.application/src/com/minres/scviewer/e4/application/parts/DesignBrowser.java
+++ b/com.minres.scviewer.e4.application/src/com/minres/scviewer/e4/application/parts/DesignBrowser.java
@@ -60,6 +60,7 @@ import org.eclipse.swt.events.SelectionEvent;
 import org.eclipse.swt.layout.GridData;
 import org.eclipse.swt.layout.GridLayout;
 import org.eclipse.swt.widgets.Composite;
+import org.eclipse.swt.widgets.Control;
 import org.eclipse.swt.widgets.Text;
 import org.eclipse.swt.widgets.ToolBar;
 import org.eclipse.swt.widgets.ToolItem;
@@ -373,9 +374,13 @@ public class DesignBrowser {
 			waveformViewerPart.addDisposeListener( new DisposeListener() {
 				@Override
 				public void widgetDisposed(DisposeEvent e) {
-					// reset tree- and tableviewer
-					resetTreeViewer();
-    			}
+					Control control = treeViewer.getControl();
+					// check if widget is already disposed (f.ex. because of workbench closing)
+					if (control == null || control.isDisposed()) { //if so: do nothing
+					}else {  //reset tree- and tableviewer
+						resetTreeViewer();
+					}
+				}
 			} );
 		}
 		this.waveformViewerPart=waveformViewerPart;