Author: Andrey Bogdanov
Write digits from 1 to 4 (each digits can be used any amount of times) into some cells so that cells with digits don't touch each other even in a point. Clues outside show the sum of the digits in the corresponding row or column.
Grid control: Click at a cell reveals the value chooser. Click at the selected value changes the state of the cell. More details about grid control are at the help page.