VertivalLayout in 7.6.0.beta2 steHeight and vertical scrollbar problem

I am having an advanced search popupbutton add-on with

final VerticalLayout popupbuttonVerticalLayout = advancedSearchLayout.get();
popupbuttonVerticalLayout.setSizeFull();
advancedSearchButton.setContent(popupbuttonVerticalLayout)

My advancedSearchLayout extends VerticalLayout with

setSizeFull();
setWidth("270px");

I am adding to that verticalLayout a header, an accordion and a footer, where accordion.setExpandRatio = 1 to expand to the whole vertical space I am having

accordion.setSizeFull();
addComponents(header, accordion, footer);
setExpandRatio(accordion, 1.0f);

Every accordion item (which is also Vertical Layout, with default width/height) is wrapped in a panel

Panel wrappingPanel = new Panel();
wrappingPanel.addStyleName(ValoTheme.PANEL_BORDERLESS);
wrappingPanel.addStyleName("wrapping-panel-accordion");
wrappingPanel.setSizeFull();

wrappingPanel.setContent(item);

so, I should get a vertical scrollbar, but I dont get it in vaadin7.6.0.beta2, whereas It works OK in any 7.5.x version. If I set wrappingPanel.setHeight = 250px I get a scrollbar, but I dont want to set it to fix height as I dont know users browser height. Scrollbar needs to be in each wrapping Panel, not the whole VerticalLayout.

Do you have any idea what has happeden with layout in vaadin 7.6.0.beta2? See attached screenshot.