my unanswered question: copy clipboard to a widget

[bup_schaefer]

I have posted this two times, but I hve no answer yet:

Hello,

with "clipboard_append" (Tkinter) I can copy the text content of a 
widget in the clipboard.

My question:
How is it possible to copy (by the program,not with ctrl-V)the 
content of the clipboard to a widget?

Many thanks for your answer,
Bruno Schäfer