I had a bit of "fun" testing out the newest rev, here are the results :D.

The LOAD button (very nice neon green effect btw) is placed in a weird spot on my screen. Maybe center it vertically ?

Also, maybe scale it with the window ? So that the entire window always has the same look. You could put a limit to how small the window can be, too.

The About/Credits button disappears when I click on it, reappears once I close the About popup. Not sure if intended ?

A few issues with the Bulk Conversion window :

1. Changing the format in the Bulk Conversion window also changes the preview in the "normal" conversion window, in the background. Shouldn't both windows be independent ?
2. The layout of the window varies depending on the format you choose, probably because it adapts to the string of text used to describe said format. Have a constant window size instead ?
3. Same as 1., but for the numbers below the preview.
   
   

I was able to completely drag the preview out of the screen, with no way of dragging it back in (except changing window size). That's probably not something you want :). Perhaps add boundaries to the box you can drag the preview in ? Like, a box with size of 1.5*mipResolution to have a bit of margin. Maybe it's too complicated to implement, in which case feel free to ignore.

On the 2 screenshots above, you can also see an issue with the "Resolution (MIP Resolution)" string, which overlaps horizontally.

On zooming previews, please change the upscale algorithm to nearest neighbour :). You cannot see the pixels with the current algorithm used. A bit like you would see it in PS.