Xdebug support

[nbsoftware]

Hello,
I recently used this image and my wordpress site is running locally and quick!
Now, I wanted to add xdebug support and be able to do step by step debugging into my custom code (mainly my theme which is under git under a wp-content root directory).
Problem is that the wordpress core files are located in the container under /usr/src/wordpress which are inaccessible to the IDE.
xdebug is connecting to my local PhpStorm, and this one breaks immediately when debugging complaining that it couldn't find the source file and no path mapping could ever make it work.
For now I'm not too sure how I could solve this.
Any idea?