1.11.5 Scrolling up issue still present on specific cases

[gwompki]

Similar case to this report viewtopic.php?t=50152 where the issue hasn't been fully ironed out.

There's seems to be a bug with the scrolling up detection depending on the window's length size, particularly when there are 3 rows of files and the window length is somewhere between 641 to 768 pixels (I say 768p because that's the max resolution of my display, so I don't really know where exactly the cutoff point is). The only way to scroll back up is to set the cursor on the scrollbar for the mouse wheel to be able to scroll up again.

Example of a window where the issue is present

xnviewmp_2026-07-07_16-42-52.png

Ini file:

xnview.zip

[xnview]

i'm not able to reproduce. Windows scaling 100%?

[gwompki]

Yeah it's a 100%. Never really messed with Window's scaling option. Other than that I'm using W10 so I'm not sure if that's factor to reproduce the issue.

And just out of curiosity I tried to reproduce the issue on a fresh install of xnviewmp on an also fresh w10 sandbox and got the same results: Three rows of items, can't scroll up once you've scrolled down. So it doesn't seem to be tied to an specific window size but the Xnview's internal browser viewing port that gets confused when the scrollbar reaches an specific size (?) and the scrolling behavior fails at that specific point.

Fresh install, point at which the scrolling up behavior shows up again:

xnviewmp_2026-07-11_13-35-05.png

[moropus]

Came here to report exactly this.
My observation, is that vertical scroll freezes when there are less than one row of files to scroll up.

[XnViewMP_4_Ever]

Same here! No matter which OS (macOS or Linux) it is impossible to scroll up, when I am at the bottom within a folder. My father experienced this before on his macOS and I wanted to correct him, but I was wrong - it is a bug and not his fault!

Now, I have experienced this on several PCs and operating systems as well. The only way is to use the scroll bar to get up again or POS1, the mouse wheel is useless!

[xnview]

Thanks to your detailed description I can reproduce the problem.

[FrankE]

I can confirm the same issue on my system.

Configuration:
- XnView MP 1.11.5
- Windows 11 25H2
- 1920 × 1080
- 100% display scaling
- Logitech M510 (Logi Options+ installed)

Behavior:
- Scrolling down in the thumbnail browser always works.
- Scrolling up often requires 3–4 attempts before the browser starts moving.
- If I move the mouse pointer over the vertical scrollbar, scrolling up works immediately and reliably again.
- The problem occurs only in the thumbnail browser. Windows Explorer and all other applications scroll normally.

Additional observation:
The issue only occurs when exactly 3 rows of thumbnails are visible.

As soon as I slightly reduce the thumbnail size so that 4 rows are visible, the problem disappears completely.

Switching back to 3 visible rows immediately brings the issue back.

Hopefully this additional information helps reproducing the bug.