Unnecessary regenerate thumbnails

Hi,

can you please not regenerate existing thumbnails when I click “generate”?

I am using plugin Crop-Thumbnails (and there are lots of other plugins) and so every existing thumbnail is original. But your plugin deletes all thumbnails and creates new thumbnails although it is not necessary – when image-100×100.jpg exists it could only generate image-100×[email protected] and not delete image-100×100.jpg and create new one.

Then it would be awesome.

Thanks,
Jiri