Someone (jleach81) came on jabber to ask how to make rectangles with rounded corners with inkscape. I'd guess that elliptical arcs are similarly hard to guess how to do.
The person arrived & left while I was away from my terminal, so I don't know whether the person didn't know what tool to use or didn't know how to use the tool to create those alternative shapes.
The tooltips of the relevant tools (with square and circle icon, respectively) already say what shapes these tools can do.
The circle-iconed tool's cursor shape indicates that it can do elliptical arcs. Perhaps the square-iconed tool's cursor shape should have a rounded rectangle cursor rather than a square-cornered rectangle as at present?
It may be useful for the secondary toolbar for rectangle to have specializations: a square, a rectangle, a (circular-)rounded rectangle, and perhaps a circular-rounded square. Similarly for the ellipse. This would be consistent with the suggestion in the "spiral???" thread that the spiral/star tool might populate the secondary toolbar with different "odd shapes" like regular polygon, star, spiral. (Message-id: <1071701170.17080.20.camel@...16...>)
I'm not sure of a good way to make it obvious that the knot editing tool can be used to change the roundedness of rectangles.
pjm.