TK with Crystal aint bad either

tcltk.cr

@[Link("tcl")]
lib LibTcl
  type Tcl_FreeProc = Void*
  fun Tcl_SetVar(interp : Tcl_Interp*, varName : LibC::Char*, newValue : LibC::Char*, flags : Int32) : LibC::Char*
  fun Tcl_Eval(interp : Tcl_Interp*, script : LibC::Char*) : Int32
  fun Tcl_CreateInterp : Tcl_Interp*
  fun Tcl_GetStringResult(interp : Tcl_Interp*) : LibC::Char*
  fun Tcl_Init(interp : Tcl_Interp*) : Void

  struct Tcl_Interp
    result : LibC::Char*
    freeProc : Tcl_FreeProc
    errorLine : Int32
  end
end

@[Link("tk")]
lib LibTk
  fun Tk_Init(interp : LibTcl::Tcl_Interp*) : Void
  fun Tk_MainLoop : Void
end

my_string = "MagicWord"
puts("The secret is '#{my_string}'")
interp = LibTcl.Tcl_CreateInterp
LibTcl.Tcl_Init(interp)
LibTk.Tk_Init(interp)
LibTcl.Tcl_SetVar(interp, "my_string", my_string, 0)

script = <<-END_SCRIPT
package require Tk
pack [button .b -text {Push Me} -command {
    tk_messageBox -message $my_string
}]
END_SCRIPT

puts LibTcl.Tcl_Eval interp, script
puts String.new(LibTcl.Tcl_GetStringResult(interp))

LibTk.Tk_MainLoop