The is also an issue in 2.5.3 with the initial position of the top thumbnail when a tour loads, it is being cropped in half instead of scrolling down to fit the window size correctly. This happens when the tour is full screen if there are enough panos to activate the scrolling arrows, but also if the tour is embedded in a page, see screen grabs:
Full screen tour:
Embedded tour example:
Think you had the same issue in an earlier version & edited the code to sort it.
Thanks a lot for reporting this issue. An event is missing when the plugin is sized, to re-position its content. We will try to fix it for next release.