geometry app question

[roadrunner]

Go to the geometry app, cut and paste this to the command line and press <Enter>:

Instruction():="GA:= point(-3.,-2.5); // c(FF000000) v(1)
GB:= point(5.3,-1.8); // c(FF000000) v(1)
GC:= point(-2.,3.3); // c(FF000000) v(1)
GD:= circumcircle(GA,GB,GC); // c(FF000000) v(1)
"
or just create any 3 points and a circumcircle.

Press <Plot>, touch Cmds/Measure/Area, then click the circle and press <Enter>

The area of the whole circle is displayed but only half the circle is shaded:

   

Does anyone know if there is a reason for only shading half of the circle or am I doing something wrong? Other shapes the whole shape is shaded when you measure area.

-road

ps. I just bought a G2 prime at Best Buy, so far my only complaint is that I cut myself opening the tamper resistant packaging