Hello! First say that I support the great work that is being done in this software, currently owner of the iOS version and the Steam version. On the other hand, commenting that the PC version has too many bugs compared to the iOS version, it is practically unusable. I love that new components have been added like an op amp or MOSFETs but honestly if the basic components don't work accordingly it's hard to build an elaborate circuit.
Outside of this, here comes my proposal to allow the possibility of making negative voltage sources. It can be the same one that already exists with negative values or as I do in practice, use two variable sources and connect the negative of one and the positive of the other to the GND and the other two ends are the +-Vcc voltages.
I hope you consider this as I tried to do it in the simulator and it's impossible. Cheers!