Hi Victor_D, I tried your approach: does not work for me, does not change anything, unfortunately.
I've said I strongly believe it's a QuickLook display issue when in Column View, grabbing the focus of the mouse and (and probably also the keyboard) and forcing the Finder Window to redraw the rightmost item being rendered.
I've got a feeling this happens when a column lists .pdf, .eml or .txt files, because QuickLook renders those files in a box that also allows scrolling with two-finger (WHAT A GREAT GUI IDEA, A SCROLLABLE BOX EMBEDDED IN A SCROLLABLE WINDOW!!!). And when you do scroll when your cursor is in that box, you can not scroll the column view in any direction: you just scroll the QuickLook preview. You have to move the mouse pointer out of the QuickLook render box to enable "column scrolling" again (that part I agree with, this makes sense and is "discoverable" by the user).
Still, Apple: can you please urgently send this hint to your best QuickLook and Finder Window engineers, and have her/him analyse finely the QuickLook routine vs the cursor positioning in the Column hierarchy?
Currently, the QuickLook rendering triggers a rightmost refresh of the column view, no matter where the horizontal sliders are positioned.
But it should be the reverse: it's the horizontal sliding that should preempt the Quicklook refresh routine. If we scrolled left (even by a single pixel), then QuickLook should be disabled. We're obviously not QuickLooking if we scrolled left.
Makes sense? Anyone confirms my intuition on the filetypes involved?
Also, huge display error in the QuickLook render box, for a PDF: you have two horizontal arrows displayed if the PDF has more than one page, but you have to scroll vertically to show the next pages. CONFUSING!