Unable to switch themes if Touch is installed

For a demo project I have the switchtheme module installed, which provides a dropdown list of installed themes to try out. It works fine until Touch is chosen the first time. After that, no other theme can be switched to. When another theme is selected and the switchtheme button is pressed, it should reload the page and use the newly selected theme. Instead, Touch always comes back as the displayed theme and Touch is always selected in the switchtheme dropdown list. The only way to get rid of it is to deactivate Touch completely. If I reactivate Touch again, the same thing happens...it immediately becomes the selected/displayed theme. It's like a zombie-rising-from-the-dead thing. I've looked at the code in Touch but can't seem to find anything that would do this, like where it might set a cookie or something. Again, it's only Touch, the other three dozen themes I have on the demo behave correctly.