DO11: Display open/close buttons at root level in tree

How I can disable these buttons in DO11 ?

They're always there now, to let you expand/collapse the new/changed root tree items (without having to double-click things, which was not easy to discover and didn't tell you if the items were empty or just collapsed).

[quote]They're always there now[/quote]Not for me. With preferences=>folder tree=>appearance=>folder tree style=>Vista / Windows 7 enabled I have small triangles that only appears when the focus is on the folder tree.

That's a separate thing. The expanders are always there, they're just not always visible in the Vista/Win7 tree style. In the past, they could be removed entirely at the root level.