<p>Alright, I have committed a fix to a local branch of mine, so this issue should be resolved in the next release.</p>
<p>I've tried to make it intelligent, however. If you double-click on a slide within the current item, it won't change the theme, but if you double-click on the item itself, it will change the theme. This is just so that you don't accidentally change the theme halfway through a song.</p>