In the Windows client, two toolbars show by default on startup. The first one is used, e.g. for showing "Remove Download(s)", "Expand Folders", etc. in "Transfers" view, but the second one never contains any buttons and therefore doesn't seem to serve any purpose. It can be hidden by right-clicking in the toolbar area and deselecting the second checkbox, but it always returns when restarting the client. Apologies is this surplus second toolbar is in fact intentional, i.e. for use in a later release.