It’s worth noting that many input fields in Krita allow entering calculations. For example when you use the transform tool and want to set the y coordinate to exactly a half of the canvas and then add a 100 pixel offset you can type 12345 / 2 + 100 into the input field (assuming 12345 is the documents height in this case).
Very useful plugin to avoid alt-tabbing! Btw how can you customize the UI buttons to decrease their width? (the calculator occupies a lil bit too much of space in my monitor)