can't read "global_w": no such variable
can't read "global_w": no such variable
    while executing
"expr {$global_w-[winfo screenwidth .]}"
    invoked from within
"BWidget::place .top 0 0 at [expr {$global_w-[winfo screenwidth .]}] $global_h"
    ("uplevel" body line 3)
    invoked from within
"uplevel \#0 $cmd"
    (procedure "NoteBook::_select" line 30)
    invoked from within
"NoteBook::_select .mainframe.frame.nb demoTree"
    (command bound to event)
