Unbind initial bind on basic widget (text)

[Askari]

Hi,
   Do I can unbind the initial bind on basic widget? (ex.: the basic widget 
Text have the bind "<Control-a>" for the return to the first caracter of 
the line; but me I don't want this!) 
   I try  'myText.unbind("<Control-a>")'    but the bind is not remove.   
:-(


Askari

N.B. I wan't disabled ALL initial bind (not just the "<Control-a>")