Lock proportions

### Is your feature request related to a problem? Please describe. Hello! I would like to resize an image from 1886 x 2411 to a new size of 400 x [something] ### Describe the solution you'd like now... what I would like was that _when I set the new size "400" and choosing to keep the aspect ratio, it would **automatically** fill "511"_ on the other field... Maybe I'm doing something wrong... ### Describe alternatives you've considered Other apps? 🙂