I did a PCB and only found out the Gnd was isolated but I did not see any unconnected Ratsnest in OpenGL mode… I had to solder a wire at the bottom for this to connect the Gnd together…
How do I prevent this in the future from happenning ?
There have been some bugs in the connection code in the new OpenGL canvas. I think they have been fixed now, but if you find a new problem please report it on the bug tracker.