Sonic Team Junior
I can't seem to reproduce the issue, even with a fresh install on a W10 virtual machine... The only thing I can think of right now is a Windows 10 update possibly breaking things, aside from that I can't really give any advice aside from the usual "Have you restarted your PC?" and "Have you tried completely uninstalling and reinstalling?".So I installed Zone Builder on a newer PC, and left click will not let me draw a line. I can start drawing a line, but no input will allow the line to actually be drawn. Not any mouse button, not any key. Rectangle Draw does nothing. All I can do is place vertices. This is a Windows 10 system.
Also, is every drawing mode broken? You mention Rectangle Draw not working, but I'm curious if the other drawing modes (especially the basic "Start Drawing" mode (Ctrl + D)) are also broken.