However, it seems awkward to know what to do with the mouse over a 90 degree corner? I click once and see the arc but then the command window prompt says "Specify Second Entity" ?
One time I clicked once to get the arc to appear and then clicked again and it set it correctly into the upper left corner but I can't do that again with the other corner. No matter where I click or how I move the mouse I can't finish the task. Also, as I move the mouse around the arc changes, not a bad thing but I don't know what to do to 'sett' the arc when I have it in the correct orientation.
There must be a correct sequence of steps to do this correctly or is just isn't going to work and that sequence isn't an obvious one.
After the first click, when you move the mouse towards the second entity the arc seeks it's direction, when it is right, do the second click. It works fine for me, though sometimes the behaviour seems a bit strange.
Some of the code is 16 years old; and some systems definitely need to be cleaned or rewritten.
The first step is putting in the effort to understand the current system
so that it can be improved or replaced.
The current developers didn't necessarily write the old systems.
It can be a lot of work to rewrite things to make a new consistent system;
and before that can happen a new system needs to be conceived.
If you have ideas for a more intuitive system
then you are encouraged to write that system down
and post it in a new topic.