After further exploration I have found that the blur plugin itself is not causing the trouble. My problem boils down to two questions:
How can I temporarily suppress the toolbar display on screens with an image- or iframe-hotspot open (i.e. to force the user to close this screen before continuing)?
and / or
How to enforce closure of these screens when a user clicks one of the toolbar buttons with these screens still open?
I would be grateful for any hints pointing me in the right direction for a solution.

Original question:

I am building a virtual tour with many hotspots using the standard multires droplet and the xml code of the “postprocessing” example in the Viewer folder. Everything is fine but for one problem:When I click the toolbar to select another theme, while an image- or iframe-hotspot is open on screen, the theme selected opens in blurred and zoomed state. The only remedy is to restart the tour. Example: www.ariederuiter.nl/krpano-vtourtest
As the tour is meant for unattended use in a museum a solution to prevent this from happening would be very welcome. i know how to remove the blur plugin but I like its effect and hope for a better solution.

Arie de Ruiter, Amsterdam