Select inaccessible if the drop down goes below the content area

I’m testing out this plugin, but have found a problem with my use-case. I have three select filters Category, tags and another tags. If I only have a single row of products remaining (after selecting a filter option for the first two filters, I can’t see the drop down for the third option. The contents of it drop below the content area so I can’t select the filter option I want. I know why this is happening – because the drop down isn’t a real HTML select box, but a hidden div with absolute positioning, but the result is that if the overall height of the filter sidebar with the bottom select box open, exceeds that of the page, the drop down is hidden.

Anybody got a work around for this?