Played with your tool a little, here is a few things I found :
Settings wont pop up when on full screen mode
Resizing a box where the right side becomes the left side (or the opposite) is not possible, it simply redo the original box. Same for top/bottom. I think this should not be the expected behavior.
Here are some suggestions :
Make Task description optional (ReactImageAnnotate component)
Make the "selector" always present (it should be the default cursor i think). Pressing a key like "W" from cursor should get us in the drawing mode and once completed, back to selector mode.
Divider between the always present and optional tools on the left side bar
Center the image by default in the Pan
For bounding box, a single click shouldn't create a 1 pixel box. Either make it so we can draw box (click -> drag -> click) or simply do nothing since it is probably a missclick
Put the label inside the annotation if the annotation of the bounding box is 100% height of the image
1 color per class, I think this should the default. Could be optional to have different colors for all.
make it possible to have a "default class" just like Labelimg. All Labelimg is missing is being able to change the default class using hotkeys!
make it impossible to put the corners outside of the image. In the gray area.
make it possible to go to the next image without comming back to the selector every time
Played with your tool a little, here is a few things I found :
Here are some suggestions :