Passive Skill Tree / Able to add more points than available

I noticed that I can place extra skill points in the passive tree, even if it exceeds my current available points, or I have zero points to spend. And it also has inconsistent colors when I confirm them. Sometimes I get a red line connection, or a blue line. I can also refund the points, but I have no idea if they're giving me any extra stats. I lost about 7000 gold this way. I can usually grab about three points before I can't anymore. The number at the top right doesnt go down, even for weapon sets, which wouldnt make sense anyway since I didn't hold cross to assign a set to the node