XnView Software

XnView MP
Switching modes
window full Viewer > Fullscreen
when switching
The screen flickers as the window gets smaller and then larger.
My eyes get tired at this time.
Switching from Fullscreen to Window full Viewer is unnatural.

XnView Classic

switching mode
Viewer <> Fullscreen
when switching
If the picture is small, the picture is broken.
In particular, if a picture drawn with black and white lines is reduced and converted to a smaller size,
The grid of lines breaks.