In MGNLUI-2673 for Magnolia 5.2 a hack was introduced where we patch PanelConnector be an EnterFriendlyPanelConnector. The hack is still present. Vaadin framework and the way shortcuts are handled has changed enough that the patch might be obsolete and hack could be removed. 

• explore which of the MGNLUI-2673 acceptance criteria were covered with the friendlyPanel hack
• try to remove the panelconnector.txt patch and see if behavior changes
• In case of regression, see if Vaadin 8 / FastNavigation add-on introduced in MGNLUI-4974 cannot handle them less invasively.