XnView Software

a) Simply take the next preset
b) without steps, gauss-Interpolate the Thumbs and accept the sice after "Enter" or forget it after "Esc"

"a)" would be easy to implement
"b)" is a "nice to have"

Bruno

Another "C". It's not another way, just another (mouse) shortcut to change the size of thumbnails without keyboard quickly.

c) Right click + wheel - the same mouse shortcut as in view mode for zooming, when using just the wheel to switch images. Perhaps also left click + wheel.