Consider sample Bézier curve with a red stroke:
Now, I want to paint the background of the whole selection area.
Is there a straight-forward way of achieving this?
This is what I get using standard fill option:
I've created the mockup by creating a rectangle with the same dimensions as the curve, then aligning and grouping the two.
Perhaps it's the only way.
However, I don't quite like edges not aligning perfectly in case of a thicker stroke:
Furthermore, I thought that the approach with rectangle is workaround-ish and does not produce accurate and scalable result. It does.
Explained in my comment to @user287001 's answer.