using fwt
using gfx

class Main {
  static Void main(){    
    textOut := Text{ 
      multiLine = true      
    }
    textIn := Text{
      multiLine = true
      text="one\ntwo"
      w := it
      onModify.add{
        textOut.text=w.text+"\nout"
      }
    }
    Window {     
      GridPane{
        textIn,textOut
      },      
    }.open    
  }
}

In textIn appear square instead of newline.

http://yfrog.com/3161594055p

On MacOS everything looks as expected. Have you tried to use \r instead?

On XP it doesn't have the block - but it doesn't have a newline either (as the code currently stands).

Replacing with

textOut.text=w.text+"\r\nout"

Works as expected.

Perhaps there's a need for sys::Env.newline or similar?