Since I haven't had much time in this I'll
1) I change settings constantly. Having the settings in its own drop down window feels like an attempt to hide complexity from me. On the one hand, I commend you for attempting to make the software more approachable. On the other, please give me the option to change it back immediately.
2) In Lubuntu when the screensaver kicks in and the monitor turns off the print stops dead. This means that Cura can be used to slice a model, but an attempt to print using it is a guaranteed failure. Is there a way to prevent this from happening? Perh