destroy forward compatibility

  # Starting in Tk 8.0, the destroy command stopped returning an error when
  # given a non-existent window as an argument.

  package require Tk
  if {[package vcompare [package provide Tk] 8] < 0} {
      rename destroy Tk4.2_destroy
      proc destroy {args} {
          catch {uplevel Tk4.2_destroy $args}
      }
  }

Category Porting