На чем удобно делать GUI?

package require Tk
pack [button .mybutton -text Пока-пока! -command exit]

// gcc hello.c -lmui
#include <exec/types.h>
#include <libraries/mui.h>

#include <proto/exec.h>
#include <proto/intuition.h>
#include <proto/muimaster.h>
#include <clib/alib_protos.h>

int main(void)
{
    Object *wnd, *app, *but;

    // GUI creation
    app = ApplicationObject,
        SubWindow, wnd = WindowObject,
            MUIA_Window_Title, "Hello world!",
            WindowContents, VGroup,
                Child, TextObject,
                    MUIA_Text_Contents, "\33cHello world!\nHow are you?",
                    End,
                Child, but = SimpleButton("_Ok"),
                End,
            End,
        End;

    if (app != NULL)
    {
        ULONG sigs = 0;

        // Click Close gadget or hit Escape to quit
        DoMethod(wnd, MUIM_Notify, MUIA_Window_CloseRequest, TRUE,
                 (IPTR)app, 2,
                 MUIM_Application_ReturnID, MUIV_Application_ReturnID_Quit);

        // Click the button to quit
        DoMethod(but, MUIM_Notify, MUIA_Pressed, FALSE,
                 (IPTR)app, 2,
                 MUIM_Application_ReturnID, MUIV_Application_ReturnID_Quit);

        // Open the window
        set(wnd, MUIA_Window_Open, TRUE);

        // Check that the window opened
        if (XGET(wnd, MUIA_Window_Open))
        {
            // Main loop
            while((LONG)DoMethod(app, MUIM_Application_NewInput, (IPTR)&sigs)
                  != MUIV_Application_ReturnID_Quit)
            {
                if (sigs)
                {
                    sigs = Wait(sigs | SIGBREAKF_CTRL_C);
                    if (sigs & SIGBREAKF_CTRL_C)
                        break;
                }
            }
        }
        // Destroy our application and all its objects
        MUI_DisposeObject(app);
    }
    
    return 0;
}