Currently WillowTree# uses .NET 3.5. It should work if you use a recent version of Mono. The only potential problem is that it might not work due to the DotNetBar library that's being used.
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Currently WillowTree# uses .NET 3.5. It should work if you use a recent version of Mono. The only potential problem is that it might not work due to the DotNetBar library that's being used.