Selena includes a nice "Create Patch..." feature that makes a GNU diff-compatible unified diff. Presumably this uses classes from com.intellij.util.diff, which are nice, but creating a patch file from Diff.Content objects is non-trivial, and it would be nice if the code to do so were moved to the openapi. I'm writing a plugin that integrates with a code review tool and creating patches is a necessary part of the plugin. (I've written my own, but I'd rather just use yours if possible.)