This is a requested feature for all 2D artists, texture painters and sculptors.
We need a way of rotating the full viewport as other softwares do, because sometimes is easier draw from left to right instead of drawing vertical, especially for lines.
There are some add-ons already for that, but these are partiall solutions and only works in some situations. We need a more general solution.
This is general problem for any mode that need to use a pen for drawing.