Setting the selection of an editable combobox ends in an error:

<verbatim>
% pack [ComboBox .c -editable 1 -values "A B C"]
% .c selection range 0 end
invalid command name "::ComboBox::selection"
</verbatim>

If one knows the path of the embedded entry widget, one may use:

<verbatim>
% .c.e selection range 0 end
</verbatim>