rgumentException: The Assembly System.Windows.Forms is referenced by UnityCoin ('Assets/Plugins/UnityCoin/UnityCoin.dll'). But the dll is not allowed to be included or could not be found. UnityEditor.AssemblyHelper.AddReferencedAssembliesRecurse (System.String assemblyPath, System.Collections.Generic.List`1 alreadyFoundAssemblies, System.String[] allAssemblyPaths, System.String[] foldersToSearch, System.Collections.Generic.Dictionary`2 cache, BuildTarget target) (at C:/buildslave/unity/build/Editor/Mono/AssemblyHelper.cs:140) UnityEditor.AssemblyHelper.AddReferencedAssembliesRecurse (System.String assemblyPath, System.Collections.Generic.List`1 alreadyFoundAssemblies, System.String[] allAssemblyPaths, System.String[] foldersToSearch, System.Collections.Generic.Dictionary`2 cache, BuildTarget target) (at C:/buildslave/unity/build/Editor/Mono/AssemblyHelper.cs:146) UnityEditor.AssemblyHelper.FindAssembliesReferencedBy (System.String[] paths, System.String[] foldersToSearch, BuildTarget target) (at C:/buildslave/unity/build/Editor/Mono/AssemblyHelper.cs:180) UnityEngine.GUIUtility:ProcessEvent(Int32, IntPtr)