I refer to the folder list on the left hand side of the contact sheet. If a folder contains more folders there will be a little grey arrow to the left of the folder pointing to the right. You can click the arrow to open the parent folder. If you select a folder, a yellow bar paints over the line but the arrow becomes almost invisible. If you move your mouse to the right and over the contact sheet section, the arrow turns grey and visible. This should be fixed so the arrow is always grey even if you keep your mouse over the sidebar.
