Flickering when comparing images during file tree scrolling.

[bear-gha]

Hello,

I’d like to thank you for the program that you’ve been maintaining for many years — I really appreciate it. Now, about an old issue that still persists up to the current version; it’s been around for quite a long time. Here are the steps to reproduce it (Windows 11 system, latest program version 2.16.52.0 X64):

1. Install the program.
2. Add two folders with images (in this example, PNG files) for comparison.
3. Open the first item and start browsing through the images by clicking “Next File” (Ctrl+F8).
4. As long as the images are within the portion of the list visible in the tree view, everything works fine. But once the scrolling in the tree view begins in the background, the image starts flickering rapidly, switching back and forth to the scrolling tree view.

In simple terms — when the list starts scrolling in the background, it appears as flickering on the screen.

[sdottaka]

This occurs because Ctrl+F8 closes the current image comparison window before opening the next one, to handle cases where the next file is a different type.
We might improve this by reusing the same window when both files are images.