Description of problem:
DebugException is thrown when Agenda view change focus while debugging.

Version-Release number of selected component (if applicable):
BRMS 5.3.0.ER2
JBDS 5.0.0.M5

How reproducible:
Follow next steps

Steps to Reproduce:
1. Start JBDS with parameters -console -consolelog -debug
2. Create new Drools project and add all sample source code.
3. Add breakpoint at line 12 in file src/main/rules/Sample.drl
4. Debug src/main/java/com/sample/DroolsTest.java as Drools application
5. When debugging stops at breakpoint open Drools Agenda view
6. On console can be seen following exception and it is thrown by changing Agenda focus state
  
Actual results:
!ENTRY org.drools.eclipse 4 120 2012-01-17 13:01:42.731
!MESSAGE Internal error in Drools Plugin: 
!STACK 1
org.eclipse.debug.core.DebugException: Error when compiling snippet return getAgenda().getFocus();: The method getFocus() is undefined for the type Agenda

	at org.drools.eclipse.debug.DebugUtil$EvaluationBlock.evaluate(DebugUtil.java:194)
	at org.drools.eclipse.debug.DebugUtil.getValueByExpression(DebugUtil.java:116)
	at org.drools.eclipse.debug.AgendaViewContentProvider.getAgendaElements(AgendaViewContentProvider.java:86)
	at org.drools.eclipse.debug.AgendaViewContentProvider.getChildren(AgendaViewContentProvider.java:54)
	at org.drools.eclipse.debug.DroolsDebugViewContentProvider.getElements(DroolsDebugViewContentProvider.java:52)
	at org.eclipse.jface.viewers.StructuredViewer.getRawChildren(StructuredViewer.java:1010)
	at org.eclipse.jface.viewers.ColumnViewer.getRawChildren(ColumnViewer.java:703)
	at org.eclipse.jface.viewers.AbstractTreeViewer.getRawChildren(AbstractTreeViewer.java:1336)
	at org.eclipse.jface.viewers.TreeViewer.getRawChildren(TreeViewer.java:391)
	at org.eclipse.jface.viewers.StructuredViewer.getFilteredChildren(StructuredViewer.java:917)
	at org.eclipse.jface.viewers.AbstractTreeViewer.getSortedChildren(AbstractTreeViewer.java:605)
	at org.eclipse.jface.viewers.AbstractTreeViewer$1.run(AbstractTreeViewer.java:805)
	at org.eclipse.swt.custom.BusyIndicator.showWhile(BusyIndicator.java:70)
	at org.eclipse.jface.viewers.AbstractTreeViewer.createChildren(AbstractTreeViewer.java:782)
	at org.eclipse.jface.viewers.TreeViewer.createChildren(TreeViewer.java:644)
	at org.eclipse.jface.viewers.AbstractTreeViewer.createChildren(AbstractTreeViewer.java:753)
	at org.eclipse.jface.viewers.AbstractTreeViewer.internalInitializeTree(AbstractTreeViewer.java:1533)
	at org.eclipse.jface.viewers.TreeViewer.internalInitializeTree(TreeViewer.java:833)
	at org.eclipse.jface.viewers.AbstractTreeViewer$5.run(AbstractTreeViewer.java:1517)
	at org.eclipse.jface.viewers.StructuredViewer.preservingSelection(StructuredViewer.java:1443)
	at org.eclipse.jface.viewers.TreeViewer.preservingSelection(TreeViewer.java:403)
	at org.eclipse.jface.viewers.StructuredViewer.preservingSelection(StructuredViewer.java:1404)
	at org.eclipse.jface.viewers.AbstractTreeViewer.inputChanged(AbstractTreeViewer.java:1510)
	at org.eclipse.jface.viewers.ContentViewer.setInput(ContentViewer.java:280)
	at org.eclipse.jface.viewers.StructuredViewer.setInput(StructuredViewer.java:1690)
	at org.drools.eclipse.debug.DroolsDebugEventHandlerView.setViewerInput(DroolsDebugEventHandlerView.java:143)
	at org.drools.eclipse.debug.DroolsDebugEventHandlerView.becomesVisible(DroolsDebugEventHandlerView.java:181)
	at org.eclipse.debug.ui.AbstractDebugView$DebugViewPartListener.partVisible(AbstractDebugView.java:179)
	at org.eclipse.ui.internal.PartListenerList2$7.run(PartListenerList2.java:172)
	at org.eclipse.core.runtime.SafeRunner.run(SafeRunner.java:42)
	at org.eclipse.core.runtime.Platform.run(Platform.java:888)
	at org.eclipse.ui.internal.PartListenerList2.fireEvent(PartListenerList2.java:55)
	at org.eclipse.ui.internal.PartListenerList2.firePartVisible(PartListenerList2.java:170)
	at org.eclipse.ui.internal.PartService.firePartVisible(PartService.java:253)
	at org.eclipse.ui.internal.WorkbenchPagePartList.firePartVisible(WorkbenchPagePartList.java:68)
	at org.eclipse.ui.internal.PartList.partVisible(PartList.java:288)
	at org.eclipse.ui.internal.PartList.access$2(PartList.java:277)
	at org.eclipse.ui.internal.PartList$1.propertyChanged(PartList.java:47)
	at org.eclipse.ui.internal.WorkbenchPartReference.fireInternalPropertyChange(WorkbenchPartReference.java:375)
	at org.eclipse.ui.internal.WorkbenchPartReference.fireVisibilityChange(WorkbenchPartReference.java:536)
	at org.eclipse.ui.internal.PartPane.setVisible(PartPane.java:318)
	at org.eclipse.ui.internal.ViewPane.setVisible(ViewPane.java:534)
	at org.eclipse.ui.internal.presentations.PresentablePart.setVisible(PresentablePart.java:180)
	at org.eclipse.ui.internal.presentations.util.PresentablePartFolder.select(PresentablePartFolder.java:270)
	at org.eclipse.ui.internal.presentations.util.LeftToRightTabOrder.select(LeftToRightTabOrder.java:65)
	at org.eclipse.ui.internal.presentations.util.TabbedStackPresentation.selectPart(TabbedStackPresentation.java:473)
	at org.eclipse.ui.internal.PartStack.refreshPresentationSelection(PartStack.java:1245)
	at org.eclipse.ui.internal.PartStack.setSelection(PartStack.java:1198)
	at org.eclipse.ui.internal.PartStack.presentationSelectionChanged(PartStack.java:834)
	at org.eclipse.ui.internal.PartStack.access$1(PartStack.java:823)
	at org.eclipse.ui.internal.PartStack$1.selectPart(PartStack.java:137)
	at org.eclipse.ui.internal.presentations.util.TabbedStackPresentation$1.handleEvent(TabbedStackPresentation.java:133)
	at org.eclipse.ui.internal.presentations.util.AbstractTabFolder.fireEvent(AbstractTabFolder.java:269)
	at org.eclipse.ui.internal.presentations.util.AbstractTabFolder.fireEvent(AbstractTabFolder.java:278)
	at org.eclipse.ui.internal.presentations.defaultpresentation.DefaultTabFolder.access$1(DefaultTabFolder.java:1)
	at org.eclipse.ui.internal.presentations.defaultpresentation.DefaultTabFolder$2.handleEvent(DefaultTabFolder.java:88)
	at org.eclipse.swt.widgets.EventTable.sendEvent(EventTable.java:84)
	at org.eclipse.swt.widgets.Widget.sendEvent(Widget.java:1258)
	at org.eclipse.swt.widgets.Widget.sendEvent(Widget.java:1282)
	at org.eclipse.swt.widgets.Widget.sendEvent(Widget.java:1267)
	at org.eclipse.swt.widgets.Widget.notifyListeners(Widget.java:1061)
	at org.eclipse.swt.custom.CTabFolder.setSelection(CTabFolder.java:2745)
	at org.eclipse.swt.custom.CTabFolder.onMouse(CTabFolder.java:1432)
	at org.eclipse.swt.custom.CTabFolder$1.handleEvent(CTabFolder.java:257)
	at org.eclipse.swt.widgets.EventTable.sendEvent(EventTable.java:84)
	at org.eclipse.swt.widgets.Widget.sendEvent(Widget.java:1258)
	at org.eclipse.swt.widgets.Display.runDeferredEvents(Display.java:3588)
	at org.eclipse.swt.widgets.Display.readAndDispatch(Display.java:3209)
	at org.eclipse.ui.internal.Workbench.runEventLoop(Workbench.java:2696)
	at org.eclipse.ui.internal.Workbench.runUI(Workbench.java:2660)
	at org.eclipse.ui.internal.Workbench.access$4(Workbench.java:2494)
	at org.eclipse.ui.internal.Workbench$7.run(Workbench.java:674)
	at org.eclipse.core.databinding.observable.Realm.runWithDefault(Realm.java:332)
	at org.eclipse.ui.internal.Workbench.createAndRunWorkbench(Workbench.java:667)
	at org.eclipse.ui.PlatformUI.createAndRunWorkbench(PlatformUI.java:149)
	at org.eclipse.ui.internal.ide.application.IDEApplication.start(IDEApplication.java:123)
	at org.eclipse.equinox.internal.app.EclipseAppHandle.run(EclipseAppHandle.java:196)
	at org.eclipse.core.runtime.internal.adaptor.EclipseAppLauncher.runApplication(EclipseAppLauncher.java:110)
	at org.eclipse.core.runtime.internal.adaptor.EclipseAppLauncher.start(EclipseAppLauncher.java:79)
	at org.eclipse.core.runtime.adaptor.EclipseStarter.run(EclipseStarter.java:344)
	at org.eclipse.core.runtime.adaptor.EclipseStarter.run(EclipseStarter.java:179)
	at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
	at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:57)
	at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
	at java.lang.reflect.Method.invoke(Method.java:616)
	at org.eclipse.equinox.launcher.Main.invokeFramework(Main.java:622)
	at org.eclipse.equinox.launcher.Main.basicRun(Main.java:577)
	at org.eclipse.equinox.launcher.Main.run(Main.java:1410)
	at org.eclipse.equinox.launcher.Main.main(Main.java:1386)
!SUBENTRY 1 org.drools.eclipse 4 120 2012-01-17 13:01:42.732
!MESSAGE Error when compiling snippet return getAgenda().getFocus();: The method getFocus() is undefined for the type Agenda


Expected results:
No exception

Additional info: