Before patch do the following: As teacher create an assignment As student submit pdf As teacher give feedback with editpdf and add rectangle with 0 width/height (select rect and click on view area, don't drag mouse) Draw circle/image etc with 0 width/height and make sure you don't see anything Save feedback and you should see divide by zero error. Apply patch and go to editpdf make sure you can't add any circle/rectangle etc with width/height < 5px. Highlight should be min 5px width Stamp should be min 40px Save feedback and you should not get divide by zero error. Test other functionalities and make sure all works as expected.