Monologue chat program

Controls.ButtonClicked = clicked
GraphicsWindow.Show()
TextWindow.WriteLine(GraphicsWindow.FontSize)
GraphicsWindow.DrawText(0,0,"Message: ")
textbox1 = Controls.AddTextBox(60,0)
button1 = Controls.AddButton("Button1",0,50)
multiline1 = Controls.AddMultiLineTextBox(0,100)
File.WriteContents("D:/test.txt","")
Controls.SetSize(multiline1,400,300)

Sub clicked
  message = "You : " + Controls.GetTextBoxText(textbox1)
  Controls.SetTextBoxText(textbox1,"")
  File.AppendContents("D:/test.txt",message)
  Controls.SetTextBoxText(multiline1,File.ReadContents("D:/test.txt"))
  computeranswer()
  File.AppendContents("D:/test.txt","Computer : " + commes)
  Controls.SetTextBoxText(multiline1,File.ReadLine("D:/test.txt",i))
EndSub


Sub computeranswer
  commes = ""
  For i = 0 To 7
    random = Math.GetRandomNumber(79)
    ans[i] = Text.GetCharacter(48 + random)
  EndFor
 
  For i = 0 To 7
    commes = commes + ans[i]
  EndFor
 
  program.Delay(1000*Math.GetRandomNumber(3))
EndSub