[Flamingo] Issues with updating ribbon gallery content

[kirill-grouchnikov]

Steps:

• Run the BasicCheckRibbon demo
• Go to the taskbar overflow, click the popup of the gallery (the one with the "A" icon) and click one of the gallery buttons
• Now click the "Update gallery" button in the right-side control panel of the menu

Exception is thrown:

Exception in thread "AWT-EventQueue-0" java.lang.ArrayIndexOutOfBoundsException: Index 1 out of bounds for length 1
	at org.pushingpixels.flamingo.internal.ui.common.BasicCommandButtonPanelUI$RowFillLayout.layoutContainer(BasicCommandButtonPanelUI.java:410)
	at java.desktop/java.awt.Container.layout(Container.java:1537)
	at java.desktop/java.awt.Container.doLayout(Container.java:1526)
	at org.pushingpixels.flamingo.internal.ui.common.BasicCommandButtonPanelUI.lambda$installListeners$2(BasicCommandButtonPanelUI.java:146)
	at java.desktop/java.awt.event.InvocationEvent.dispatch(InvocationEvent.java:313)
	at java.desktop/java.awt.EventQueue.dispatchEventImpl(EventQueue.java:770)
	at java.desktop/java.awt.EventQueue$4.run(EventQueue.java:721)
	at java.desktop/java.awt.EventQueue$4.run(EventQueue.java:715)
	at java.base/java.security.AccessController.doPrivileged(AccessController.java:391)
	at java.base/java.security.ProtectionDomain$JavaSecurityAccessImpl.doIntersectionPrivilege(ProtectionDomain.java:85)
	at java.desktop/java.awt.EventQueue.dispatchEvent(EventQueue.java:740)
	at java.desktop/java.awt.EventDispatchThread.pumpOneEventForFilters(EventDispatchThread.java:203)
	at java.desktop/java.awt.EventDispatchThread.pumpEventsForFilter(EventDispatchThread.java:124)
	at java.desktop/java.awt.EventDispatchThread.pumpEventsForHierarchy(EventDispatchThread.java:113)
	at java.desktop/java.awt.EventDispatchThread.pumpEvents(EventDispatchThread.java:109)
	at java.desktop/java.awt.EventDispatchThread.pumpEvents(EventDispatchThread.java:101)
	at java.desktop/java.awt.EventDispatchThread.run(EventDispatchThread.java:90)