quicklook appex scrollbar on bigsur

I have a custom QLPreviewingController with a NSScrollView.
When I click with the mouse anywhere inside the ql preview view I can drag the window. This prevent to drag the scrollbar.
The problem exists only on big sur with custom quicklook appex.

Not an answer as such: I have the same issue — under Catalina as well as Big Sur — but I see that it has been fixed in Monterey. Try your code under the Monterey dev beta.

quicklook appex scrollbar on bigsur
 
 
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