by [Theo Verelst]



 for {set i 0} {$i<5} {incr i} {
    set o {};
    for {set j 7} {$j>=0} {incr j -1} {
       set k [tag_and "display dot x$i y$j"] ;
       if {[$mc itemcget $k -fill] == "red"} { set ii 1 } {set ii 0} ;
       append o $ii
    } ;
    puts [format {%x} [fromBinary $o]] 
 }