goldgraeber: "I have a problem using it: I see the + sign adding empty lines after some patches that were already present, but I can neither type nor paste into these fields"
Hi Goldgraeber, after adding empty rows with the "+" button, you should be able to write on the cells and pasting code just double clicking on them. ( if there are no already edited rows, first avaliable row will be the 1st one, if there are already some rows, the new one created will be the one after the last edited row.
If you want to create your own set of patches, just go to the upper part of the app, write a name for your set in "New set name", and click on "add set", now you can select your new set on the popup menu.
If you want to modify an existing set, just modify what you need and then press the "Save set" button.
EDIT: Tested on Yosemite 10.10.3 and Mavericks 10.9.5, no problems editing new cells so far.