Fix bug in windows_info:clear.

diff --git a/windows_info.tcl b/windows_info.tcl
index be0c399ec56c43d5c7d6638ae764de167b515638..f005d774fd09d76c93d9999b82feca1ffea700f4 100644 (file)
--- a/windows_info.tcl
+++ b/windows_info.tcl
@@ -9,7 +9,9 @@ object_class windows_info {
     member windows {}
     method clear {} {
        foreach w $slot(windows) {
-           unset slot($w.class)
+           if [info exists slot($w.class)] {
+               unset slot($w.class)
+           }
        }
        set slot(windows) {}
     }