Reporting dashboard stops responding when a section is opened twice

Any reports section can only be opened once. When you try to open a section for the second time, nothing happens, and an ERROR is logged. After that happened, no section can be opened anymore, not even sections that have not been opened before.

Steps to reproduce:
1. refresh the CMS (F5)
2. navigate to any section in the reporting dashboard (e.g. 'Broken Links')
3. click 'Reports' in the breadcrumb
4. open the same section again

Expected: the same section is shown
Actual: nothing happens, and the following stacktrace is logged (when running in Wicket development mode, the stacktrace is shown in the browser itself):

[INFO] [talledLocalContainer] 30.11.2012 17:18:08 ERROR [org.apache.wicket.RequestCycle.logRuntimeException():1558] Error attaching this container for rendering: [MarkupContainer [Component id = panel]]
[INFO] [talledLocalContainer] org.apache.wicket.WicketRuntimeException: Error attaching this container for rendering: [MarkupContainer [Component id = panel]]
[INFO] [talledLocalContainer] at org.apache.wicket.MarkupContainer.onBeforeRenderChildren(MarkupContainer.java:1789)
[INFO] [talledLocalContainer] at org.apache.wicket.Component.onBeforeRender(Component.java:4001)
[INFO] [talledLocalContainer] at org.apache.wicket.Component.internalBeforeRender(Component.java:1069)
[INFO] [talledLocalContainer] at org.apache.wicket.Component.beforeRender(Component.java:1103)
[INFO] [talledLocalContainer] at org.apache.wicket.MarkupContainer.onBeforeRenderChildren(MarkupContainer.java:1777)
[INFO] [talledLocalContainer] at org.apache.wicket.Component.onBeforeRender(Component.java:4001)
[INFO] [talledLocalContainer] at org.hippoecm.frontend.service.render.AbstractRenderService.onBeforeRender(AbstractRenderService.java:527)
[INFO] [talledLocalContainer] at org.onehippo.cms7.reports.ReportsPerspective.onBeforeRender(ReportsPerspective.java:93)
[INFO] [talledLocalContainer] at org.apache.wicket.Component.internalBeforeRender(Component.java:1069)
[INFO] [talledLocalContainer] at org.apache.wicket.Component.beforeRender(Component.java:1103)
[INFO] [talledLocalContainer] at org.apache.wicket.Component.prepareForRender(Component.java:2297)
[INFO] [talledLocalContainer] at org.apache.wicket.Component.prepareForRender(Component.java:2329)
[INFO] [talledLocalContainer] at org.apache.wicket.ajax.AjaxRequestTarget.respondComponent(AjaxRequestTarget.java:853)
[INFO] [talledLocalContainer] at org.apache.wicket.ajax.AjaxRequestTarget.respondComponents(AjaxRequestTarget.java:680)
[INFO] [talledLocalContainer] at org.apache.wicket.ajax.AjaxRequestTarget.respond(AjaxRequestTarget.java:590)
[INFO] [talledLocalContainer] at org.apache.wicket.request.AbstractRequestCycleProcessor.respond(AbstractRequestCycleProcessor.java:105)
[INFO] [talledLocalContainer] at org.hippoecm.frontend.PluginRequestCycleProcessor.respond(PluginRequestCycleProcessor.java:74)
[INFO] [talledLocalContainer] at org.apache.wicket.RequestCycle.processEventsAndRespond(RequestCycle.java:1287)
[INFO] [talledLocalContainer] at org.apache.wicket.RequestCycle.step(RequestCycle.java:1358)
[INFO] [talledLocalContainer] at org.apache.wicket.RequestCycle.steps(RequestCycle.java:1465)
[INFO] [talledLocalContainer] at org.apache.wicket.RequestCycle.request(RequestCycle.java:545)
[INFO] [talledLocalContainer] at org.apache.wicket.protocol.http.WicketFilter.doGet(WicketFilter.java:486)
[INFO] [talledLocalContainer] at org.apache.wicket.protocol.http.WicketFilter.doFilter(WicketFilter.java:319)
[INFO] [talledLocalContainer] at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:235)
[INFO] [talledLocalContainer] at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:206)
[INFO] [talledLocalContainer] at org.hippoecm.frontend.plugins.login.ConcurrentLoginFilter.doFilter(ConcurrentLoginFilter.java:54)
[INFO] [talledLocalContainer] at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:235)
[INFO] [talledLocalContainer] at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:206)
[INFO] [talledLocalContainer] at org.apache.catalina.core.StandardWrapperValve.invoke(StandardWrapperValve.java:233)
[INFO] [talledLocalContainer] at org.apache.catalina.core.StandardContextValve.invoke(StandardContextValve.java:191)
[INFO] [talledLocalContainer] at org.apache.catalina.core.StandardHostValve.invoke(StandardHostValve.java:127)
[INFO] [talledLocalContainer] at org.apache.catalina.valves.ErrorReportValve.invoke(ErrorReportValve.java:102)
[INFO] [talledLocalContainer] at org.apache.catalina.valves.AccessLogValve.invoke(AccessLogValve.java:589)
[INFO] [talledLocalContainer] at org.apache.catalina.core.StandardEngineValve.invoke(StandardEngineValve.java:109)
[INFO] [talledLocalContainer] at org.apache.catalina.connector.CoyoteAdapter.service(CoyoteAdapter.java:291)
[INFO] [talledLocalContainer] at org.apache.coyote.http11.Http11Processor.process(Http11Processor.java:859)
[INFO] [talledLocalContainer] at org.apache.coyote.http11.Http11Protocol$Http11ConnectionHandler.process(Http11Protocol.java:602)
[INFO] [talledLocalContainer] at org.apache.tomcat.util.net.JIoEndpoint$Worker.run(JIoEndpoint.java:489)
[INFO] [talledLocalContainer] at java.lang.Thread.run(Thread.java:662)
[INFO] [talledLocalContainer] Caused by: java.lang.UnsupportedOperationException: Cannot remove an item once added
[INFO] [talledLocalContainer] at org.wicketstuff.js.ext.ItemsRepeater$ExtItem.remove(ItemsRepeater.java:27)
[INFO] [talledLocalContainer] at org.apache.wicket.MarkupContainer.addedComponent(MarkupContainer.java:978)
[INFO] [talledLocalContainer] at org.apache.wicket.MarkupContainer.add(MarkupContainer.java:142)
[INFO] [talledLocalContainer] at org.wicketstuff.js.ext.ItemsRepeater.add(ItemsRepeater.java:50)
[INFO] [talledLocalContainer] at org.wicketstuff.js.ext.ExtContainer.add(ExtContainer.java:105)
[INFO] [talledLocalContainer] at org.onehippo.cms7.reports.layout.portal.PortalPanel.onBeforeRender(PortalPanel.java:76)
[INFO] [talledLocalContainer] at org.apache.wicket.Component.internalBeforeRender(Component.java:1069)
[INFO] [talledLocalContainer] at org.apache.wicket.Component.beforeRender(Component.java:1103)
[INFO] [talledLocalContainer] at org.apache.wicket.MarkupContainer.onBeforeRenderChildren(MarkupContainer.java:1777)
[INFO] [talledLocalContainer] ... 38 more