line 48 af AboutWindow.cs forum link is old one

https://forum.unity.com/threads/released-mapmagic-2-infinite-procedural-land-generator.875470/

not

using (Cell.LineStd) Draw.URL(" - Forum Thread", url:"http://forum.unity3d.com/threads/map-magic-a-node-based-procedural-and-infinite-map-generator-for-asset-store.344440/");