In the installation window, add an option (selected by default) to train the OCR automatically. If you wanted, this could feature a selection between the default languages, however defaulting to Comic Sans would suffice. This would reduce the amount of stuff to do during setup, and would ensure that the OCR is (almost) always trained. If anyone else wants to tackle this issue and has questions abo

The Invert Colors option in the menu bar currently takes a lot of time to give an output (especially on larger screens). Because of this, the application gives the user an illusion that it has frozen and the user might quit the application, losing his/her progress.

A suggestion to this would be using the flood fill algorithm which is already being used in the fill bucket feature.
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Implementing an nested div in all components is cumbersome. Introduce a 3D border component.