What does the following syntax produce for you? t = widget_base() b = widget_button(t, value = filepath('open.bmp', subdir = ['resource', 'bitmaps']), /bitmap) widget_control, t, /realize

Yes, I write it as your. but it didn't work unless in IDL7.1.2. I think it maybe the question of version

There hasn't been a change in syntax in IDL between versions. Perhaps your installation directory or path has been modified. f = filepath('open.bmp', subdir = ['resource', 'bitmaps']) print, f ; does this output look correct, for the version of IDL you are running? print, file_test(f) ; does the file exist? What is the exact error you're seeing? Is there a message, or does the button simply fail to render?