Solution is deleting the "#class-name" from the calls of ::Widget::cget and ::Widget::configure, but only outside of "create" command. This is needed for passwddlg.tcl, progressdlg.tcl and font.tcl.

Second, for BWidget knows the command "use" for SelectColor, please add in pkgInit.tcl the command "::SelectColor::use" right at the end of the definition list for it.