When scrolling horizontally, the column labels shift as well. See https://www.squirrel.nl/pub/xfer/uploads/3CXNHoycd45VtV6JLUv8qj1A.37.16.mkv Fedora 33 with 3.99.0.138, both gtk3 branch and gtk3tree branch.
That's an issue with the old GtkCTree widget still used by the summaryview and happens (at least) with the wayland display server or on mswin. Currently only the folderview has been ported to a newer GtkTreeView widget (done in the gtk3tree branch), the summaryview is still on the TODO-list.
*** Bug 4562 has been marked as a duplicate of this bug. ***
This will be fixed when bug #4344 is completed. *** This bug has been marked as a duplicate of bug 4344 ***
*** Bug 4654 has been marked as a duplicate of this bug. ***
*** Bug 4655 has been marked as a duplicate of this bug. ***