Custom theme

Currently custom theming is not supported by the platform.
But there are some work-arounds. I use my personal theme, too.

Let me explain step by step how I did it:

- Create a copy of folder
..\PortableApps\PortableApps.com\App\Graphics
- Now choose one of the available themes in
..\PortableApps\PortableApps.com\App\Graphics\Themes
(DefaultDark f.e.) and modify the files according to your theme
You mentioned that you are an experienced themer so you will know which files to modify.
- After all go to Options -> Designs in the Portable Apps menu and set the theme to the one you modified before. Done!

I hope this helps.
Feel free to come back for further questions if there are any.

Kind regards