TreeGrid with Reindeer theme


We have a Vaadin application that used version 7.x and as a customized theme ,a one that is based on Reindeer Theme. We followed the documentation about migration of Vaadin application from 7.x to 8.x and everything works well. And we continued using our customized theme. Currently, i have to develop a new view with the new Vaadin 8.1 component “TreeGrid” which suits our need to explore a defined directory (a.k.a File System explorer in the Sampler,but i am facing problems with the style of the TreeGrid. Please note that in the Sampler application, when choosing “Reindeer” as a theme for the component, we can’t expand/collapse items,we can’t resize columns, the sort icons are not displayed… What i tried to do is to recuperate the Valo styling for the TreeGrid component from the github repository and to integrate it to our theme, and doing that corrected the fact that i couldn’t even select an item,but the resize of the columns and sort icons are not corrected. Would you please point me to some resources that explains how to use new Vaadin 8.x component with the default Vaadin 7.x theme “Reindeer”? Or how to do it?

Thank you in advance, Best regards,
Best Regards,