>I saved your script as "label.rb" and "button.rb". 
>But, unfortunately, I couldn't re-generate your trouble.
>Of course, if the script is saved as "tk/label.rb" on the directory 
>which has higher priority than the Ruby/Tk system directory, 
>it will have to generate troubles. 
>Please check your $LOAD_PATH and $LOADED_FEATURES. 

Save it under any directory (folder) as you like on the name 'button.rb'
Of couse, it has no problem to run it, but try move your mouse cursor
to the generate Tk window.

Then you will get this error message window:
Error: unknown option "-state"
[OK]  [Skip Messages]  [Details>>]

Click on detail, here is the detail error message:
unknown option "-state"
unknown option "-state"
    while executing
"$w cget -state"
    (procedure "tk::ButtonEnter" line 3)
    invoked from within
"tk::ButtonEnter ."
    (command bound to event)

I am using now Tcl/Tk 8.4, and still have this problem.
Again, save to 'button.rb' or 'scale.rb' and no problem to run it,
but move the mouse cursor to the main window (ex. move to the "Hello" label )
then this error dialog message araise...

Thank you.