Rounded corner is a very frequent element in, for example, bag construction. To calculate the length of matching detail, one need to know the length of the rounding arc. For 90 degree corner it is L = PI * R / 2 and can't be added using current instruments. This makes arcs unusable for rounded corners. Current workaround is using Bezier curves with C=0.5*R and is suboptimal quirk at best.
Issue #926 closed