I think that Dream Maker should open external environments or their corresponding files, in entirely new windows, instead of replacing the existing one you have open. This would work just like opening library files. I think that when you go to File -> New Environment, Open Environment, or choose a Recent Environment, Dream Maker should open this in a new instance of it, as an entirely new window, without closing what you are currently working on.
This would also apply to File -> Open, to a lesser extent, in that it would open a new window only if what you are opening belonged to a different environment or project.
I am suggesting this because I don't like the fact that Dream Maker tries to close what you are currently working on every time you open a new project. Currently, the only way to get around this is to open a project from Windows Explorer, but that's not very convenient. Dream Maker already does this for library files, so why not other environments as well? Overall, it would be a more flexible program if it did this.
This is related to another suggestion on having tabs for files within the same project, which I also support. However, I think that for it to work properly, support for opening environments in separate windows needs to happen first.
Anyway, let me know what you think.