wmcliphist 0.6 contains new function called "auto take up". When enabled, wmcliphist become a selection owner when new content appears in clipboard. This makes selection content independent on application which copied it previously - it will persist even if this application ends (without recalling it from wmcliphist's history menu). But it seems that some applications copy text into clipboard during mouse drag instead after mouse button is released. This forces wmcliphist to take up selection content and thus application can cancel actual selection. This is rather problem of an application than wmcliphist, but it can be solved easily: just disable auto take up feature with following line in your ~/.wmcliphistrc: auto_take_up no