Selecting text through different CSS-Region flows

This text contains a footnote as a nested region what is diplayed below the article. (1) If you start selecting text from this article until somewhere in the footnote and then click somewhere, the selection should be cleared.
(1) This is a footnote. Footnotes can be quite long and go over several lines. This footnote is nested inside the text above and displayed here with the help of css-regions.