listboxs and scrollbars in TCL

Hi !

Anyone can tell me how to controll two listboxes with only one scrollbar in TCL? I have tried the following but it didn't work:

listbox .listw.list -width 25 -height 25 -yscrollcommand {.listw.scroll set}
listbox .listw.list2 -width 25 -height 25 -yscrollcommand {.listw.scroll set}
scrollbar .listw.scroll -command {.listw.list2 yview;.listw.list yview}

Thanks!

Pablo.