I actually tried to run it through Mono, but it seems that the use of PresentationFramework 184.108.40.206 (WPF), which is not currently supported by Mono, is preventing it running. Currently Mono does not support, nor plan to support WPF. I am not a .NET developer so forgive me if this seems a little naive, but would it be difficult to create a version of the modeler that is Mono compliant (i.e. using gtk# instead of WPF) that would then actually run on ALL platforms?
The Modeler uses a Windows-only dockable window library. There is no obvious alternative on Mono. Windows Presentation Foundation (WPF) is also used more and more and this is indeed not supported on Mono. Creating a GUI without these libraries would result in a Modeler that does not look as good and work as pleasantly as it does now. That would mean we would have to support two versions: the current, Windows-optimized version and a Mono-based version for Mac and Linux. And the Modeler on the Mac/Linux would not 'feel' like a Mac/Linux application at all.
The only option I see in the distant future is a web-based solution where every platform gets the same interface.
Sadly, currently, only with virtual machines.