Is your feature request related to a problem? Please describe.
A fairly simple problem. Progress Textures have a "slanted" option, and I think Progress Bars should have the same option with the same functionality.

Describe the solution you'd like
Add "Slanted" option to Progress Bars.

Describe alternatives you've considered
No alternatives.

That can't work with various other features of progress bars.

Can you explain which features would not be compatible?

For exaomple the border/model and tick sub element.