[243263] NPE on expanding a filter

rse/plugins/org.eclipse.rse.ui/UI/org/eclipse/rse/ui/SystemBasePlugin.java

@@ -40,6 +40,7 @@ import org.eclipse.swt.graphics.Image;
 import org.eclipse.swt.widgets.Display;
 import org.eclipse.swt.widgets.MessageBox;
 import org.eclipse.swt.widgets.Shell;
+import org.eclipse.ui.IWindowListener;
 import org.eclipse.ui.IWorkbench;
 import org.eclipse.ui.IWorkbenchWindow;
 import org.eclipse.ui.PlatformUI;
@@ -61,6 +62,13 @@ public abstract class SystemBasePlugin extends AbstractUIPlugin
      */
 	protected static Logger log = null;
 
+	/**
+	 * Active workbench window
+	 */
+	private static volatile IWorkbenchWindow activeWindow = null;
+	private static volatile IWorkbenchWindow previousActiveWindow = null;
+	private static IWindowListener windowListener = null;
+
 	// instance variables
     private Hashtable imageDescriptorRegistry = null;
 
@@ -112,7 +120,7 @@ public abstract class SystemBasePlugin extends AbstractUIPlugin
 			if (Display.getCurrent() != null) {
 				return wb.getActiveWorkbenchWindow();
 			}
-			// otherwise, get a list of all the windows, and simply return the first one
+			// otherwise, get a list of all the windows, and try to guess which one is right
 			// KM: why do we need this??
 			else {
 				// for bug 244454, this ends up returning the wrong window
@@ -126,18 +134,80 @@ public abstract class SystemBasePlugin extends AbstractUIPlugin
 				// will fail if we make the change now
 				//
 				IWorkbenchWindow[] windows = PlatformUI.getWorkbench().getWorkbenchWindows();
-				
 				if (windows != null && windows.length > 0) {
+					if (windows.length == 1) {
 						return windows[0];
+					} else {
+						IWorkbenchWindow bestCandidate = windows[0];
+						int candidateRank = 0;
+						for (int i = 0; i < windows.length; i++) {
+							if (windows[i] == activeWindow) {
+								return activeWindow;
+							} else if (windows[i] == previousActiveWindow) {
+								//Windows get deactivated when a sub-dialog is opened or user switches
+								//to another application. Such action still makes the previous window
+								//the best candidate for the active one.
+								bestCandidate = previousActiveWindow;
+								candidateRank=10;
+							} else if (windows[i].getActivePage()!= null && candidateRank==0) {
+								bestCandidate = windows[i];
+								candidateRank = 1;
+							}
+						}
+						return bestCandidate;
+					}
+				}
+			}
 		}
-				else {
 		return null;
 	}
+
+	private static class WindowListener implements IWindowListener {
+		public void windowActivated(IWorkbenchWindow window) {
+			activeWindow = window;
+			previousActiveWindow = null; // not needed any more, allow gc
+		}
+
+		public void windowDeactivated(IWorkbenchWindow window) {
+			if (window == activeWindow) {
+				previousActiveWindow = activeWindow;
+				activeWindow = null;
+			}
 		}
 
+		public void windowClosed(IWorkbenchWindow window) {
+			windowDeactivated(window);
+		}
+
+		public void windowOpened(IWorkbenchWindow window) {
+		}
+	}
+
+	private static void addWindowListener() {
+		synchronized (WindowListener.class) {
+			if (windowListener == null) {
+				try {
+					IWorkbench wb = PlatformUI.getWorkbench();
+					windowListener = new WindowListener();
+					wb.addWindowListener(windowListener);
+				} catch (IllegalStateException e) {
+					/* will try again later when workbench becomes available */
+					System.out.println("Workbench not yet available"); //$NON-NLS-1$
+				}
+			}
+		}
+	}
+
+	private static void removeWindowListener() {
+		synchronized (WindowListener.class) {
+			if (windowListener != null) {
+				try {
+					IWorkbench wb = PlatformUI.getWorkbench();
+					wb.removeWindowListener(windowListener);
+				} finally {
+					windowListener = null;
+				}
 			}
-		else {
-			return null;
 		}
 	}
 
@@ -541,12 +611,15 @@ public abstract class SystemBasePlugin extends AbstractUIPlugin
 	    	log = LoggerFactory.getLogger(this);
 	    	log.logInfo("Loading " + this.getClass()); //$NON-NLS-1$
 	    }
+
+	    addWindowListener();
     }
 
     /**
      * @see org.osgi.framework.BundleActivator#stop(org.osgi.framework.BundleContext)
      */
     public void stop(BundleContext context) throws Exception {
+    	removeWindowListener();
     	logDebugMessage(this.getClass().getName(), "SHUTDOWN"); //$NON-NLS-1$
    	    LoggerFactory.freeLogger(this);
         super.stop(context);
@@ -569,6 +642,8 @@ public abstract class SystemBasePlugin extends AbstractUIPlugin
 		IWorkbench wb = null;
 		try {
 			wb = PlatformUI.getWorkbench();
+			if (windowListener == null)
+				addWindowListener();
 		}
 		catch (Exception exc)
 		{

rse/plugins/org.eclipse.rse.ui/UI/org/eclipse/rse/ui/operations/SystemFetchOperation.java

@@ -303,16 +303,17 @@ public class SystemFetchOperation extends JobChangeAdapter implements IRunnableW
 		Object[] children = null;
   	  	// we first test to see if this is an expand-to filter in effect for this
   	  	//  object, and if so use it...
-  	  	if (_adapter instanceof ISystemRemoteElementAdapter)
+  	  	if ((_part==null || _part instanceof SystemViewPart) && _adapter instanceof ISystemRemoteElementAdapter)
   	  	{
   	  		class GetExpandToFilter implements Runnable
   	  		{
   	  			private String expandToFilter = null;
   	  			public void run()
   	  			{
-  	  				// fetching part here ourselves, because right now there's no guarantee that _part will be the correct one
+  	  				// fetching part here ourselves, because the correct part can not always be determined from a background Thread
   	  				// see bug 244454 for details
-  	  				IWorkbenchPart activePart = null;
+  	  				IWorkbenchPart activePart = _part;
+  	  				if (activePart==null) {
   	  					IWorkbenchWindow win = SystemBasePlugin.getActiveWorkbenchWindow();
   		  				if (win != null){
 	  	  					IWorkbenchPage page = win.getActivePage();
@@ -323,6 +324,7 @@ public class SystemFetchOperation extends JobChangeAdapter implements IRunnableW
   	  							}
   		  					}
 	  	  				}
+  	  				}
   	  				
   	  				if (activePart instanceof SystemViewPart){
   	  					SystemView viewer = ((SystemViewPart)activePart).getSystemView();