There is error message / warning after these steps:

1. Create sample jBPM Project, be in Package Explorer
2. Open simple.jpdl.xml in package explorer
3. (You can wait as long as you want)
4. Open hibernate.cfg.xml or any other file type (except jbpm process)

java.lang.RuntimeException: WARNING: Prevented recursive attempt to activate part org.eclipse.ui.views.PropertySheet while still in the middle of activating part org.jbpm.gd.jpdl.editor
at org.eclipse.ui.internal.WorkbenchPage.setActivePart(WorkbenchPage.java:3487)
at org.eclipse.ui.internal.WorkbenchPage.requestActivation(WorkbenchPage.java:3077)
at org.eclipse.ui.internal.PartPane.requestActivation(PartPane.java:279)
at org.eclipse.ui.internal.PartPane.handleEvent(PartPane.java:237)
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:1263)
at org.eclipse.swt.widgets.Shell.setActiveControl(Shell.java:1533)
at org.eclipse.swt.widgets.Control.sendFocusEvent(Control.java:3403)
at org.eclipse.swt.widgets.Control.gtk_event_after(Control.java:2760)
at org.eclipse.swt.widgets.Widget.windowProc(Widget.java:1738)
at org.eclipse.swt.widgets.Control.windowProc(Control.java:4796)
at org.eclipse.swt.widgets.Display.windowProc(Display.java:4360)
at org.eclipse.swt.internal.gtk.OS._gtk_widget_grab_focus(Native Method)
at org.eclipse.swt.internal.gtk.OS.gtk_widget_grab_focus(OS.java:12672)
at org.eclipse.swt.widgets.Control.forceFocus(Control.java:2170)
at org.eclipse.swt.widgets.Composite.forceFocus(Composite.java:526)
at org.eclipse.swt.widgets.Control.forceFocus(Control.java:2163)
at org.eclipse.swt.widgets.Control.setFocus(Control.java:3760)
at org.eclipse.swt.widgets.Composite.setFocus(Composite.java:1372)
at org.eclipse.swt.widgets.Composite.setFocus(Composite.java:1370)
at org.eclipse.swt.widgets.Composite.setFocus(Composite.java:1370)
at org.eclipse.swt.widgets.Composite.setFocus(Composite.java:1370)
at org.eclipse.swt.widgets.Control.fixFocus(Control.java:160)
at org.eclipse.swt.widgets.Control.setVisible(Control.java:4156)
at org.eclipse.ui.part.PageBook.showPage(PageBook.java:118)
at org.eclipse.ui.part.PageBookView.showPageRec(PageBookView.java:977)
at org.eclipse.ui.part.PageBookView.partActivated(PageBookView.java:756)
at org.eclipse.ui.views.properties.PropertySheet.partActivated(PropertySheet.java:325)
at org.eclipse.ui.part.PageBookView$4.partActivated(PageBookView.java:1010)
at org.eclipse.ui.internal.PartListenerList2$1.run(PartListenerList2.java:70)
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.firePartActivated(PartListenerList2.java:68)
at org.eclipse.ui.internal.PartService.firePartActivated(PartService.java:192)
at org.eclipse.ui.internal.PartService.setActivePart(PartService.java:306)
at org.eclipse.ui.internal.WorkbenchPagePartList.fireActivePartChanged(WorkbenchPagePartList.java:57)
at org.eclipse.ui.internal.PartList.setActivePart(PartList.java:136)
at org.eclipse.ui.internal.WorkbenchPage.setActivePart(WorkbenchPage.java:3537)
at org.eclipse.ui.internal.WorkbenchPage.requestActivation(WorkbenchPage.java:3077)
at org.eclipse.ui.internal.PartPane.requestActivation(PartPane.java:279)
at org.eclipse.ui.internal.EditorPane.requestActivation(EditorPane.java:98)
at org.eclipse.ui.internal.PartPane.handleEvent(PartPane.java:237)