I've turned 'line stipple' off when rendering a circle on Unix platforms.  I don't know if it's just the driver on my graphics card for Linux or not but it makes the circles almost invisible.  It also leaves three ghost circles rather than one solid circle.  If this stuffs up other people's rendering, please let me know.  If this is the case then I will add a parameter to the 'drawing' options to have this turned on or off.  This change turns it off for Linux but leaves it on for Windows.  I did this because I could see that, on Windows, the circles render just fine as is.
I've turned 'line stipple' off when rendering a circle on Unix platforms.  I don't know if it's just the driver on my graphics card for Linux or not but it makes the circles almost invisible.  It also leaves three ghost circles rather than one solid circle.  If this stuffs up other people's rendering, please let me know.  If this is the case then I will add a parameter to the 'drawing' options to have this turned on or off.  This change turns it off for Linux but leaves it on for Windows.  I did this because I could see that, on Windows, the circles render just fine as is.

satovey/heekscad,Funcan/heekscad,satovey/heekscad,satovey/heekscad,satovey/heekscad,haiqiangwang/heekscad,haiqiangwang/heekscad,Funcan/heekscad,haiqiangwang/heekscad,haiqiangwang/heekscad,Funcan/heekscad,Funcan/heekscad