Lightzone is fairly new to the open-source world since it used to be a commercial software. I believe it transitioned to be open-source just early this year.
It's similar to Raw Therapee (RT) which we have now as a Portable App, but I think it has a bit more editing options. Though I think RT has more demosaic options to process RAW files, Lightzone however has that Adobe Lightroom and Corel Aftershot feel to it. I specially like the ability to custom select parts of your image which you only want processed as opposed to adjusting the whole image. So basically you can lighten up just sections of the image instead of the whole thing. Anyway, I've been using it for about two weeks now and I have not run into problems thus far.
I hope you consider Lighzone as a PortableApp and that it is possible to add this in.
Thank you very much and have a great day.