The Issue tracker serves mainly as a place to report bugs and request new features. Please do not abuse it as a general questions or troubleshooting location.
For that matter you can always use the mpdf tag at Stack Overflow.
Pull requests should be always based on the default development branch except for backports to older versions.
Use an aptly named feature branch for the Pull request.
Only files and lines affecting the scope of the Pull request must be affected.
Make small, atomic commits that keep the smallest possible related code changes together.
Code should be accompanied by a unit test testing expected behaviour.
When updating a PR, do not create a new one, just git push --force
to your former feature branch, the PR will
update itself.