GUI app with nim

[merlin]

I am trying wxnim just now. I have followed the instructions in Readme
    cd examples/genuimacro

nim cpp -r controlgallery.nim but the compiler exits with this 
wxnim-master/wxnim/private/object.nim(37, 78) Error: invalid indentation

I tried to edit the code, re-enter the indentation as tab (not allowed) and as 
spaces (2 or 3), nothing works. I think I am missing something about nim 
syntax.