* tests/listbox.test: Added a test to check that the topIndex is

update when items are removed from the listvar variable.

* generic/tkListbox.c: Added a check the updates the topIndex when
items are removed from the listvar variable.

2 files changed, 27 insertions, 2 deletions

diff --git a/generic/tkListbox.c b/generic/tkListbox.c
index ced0620..50e7652 100644
--- a/generic/tkListbox.c
+++ b/generic/tkListbox.c
@@ -11,7 +11,7 @@
  * See the file "license.terms" for information on usage and redistribution
  * of this file, and for a DISCLAIMER OF ALL WARRANTIES.
  *
- * RCS: @(#) $Id: tkListbox.c,v 1.12 1999/11/24 00:20:13 ericm Exp $
+ * RCS: @(#) $Id: tkListbox.c,v 1.13 1999/11/24 01:09:07 ericm Exp $
  */
 
 #include "tkPort.h"
@@ -3195,6 +3195,12 @@ ListboxListVarProc(clientData, interp, name1, name2, flags)
 
     if (oldLength != listPtr->nElements) {
 	listPtr->flags |= UPDATE_V_SCROLLBAR;
+	if (listPtr->topIndex > (listPtr->nElements - listPtr->fullLines)) {
+	    listPtr->topIndex = listPtr->nElements - listPtr->fullLines;
+	    if (listPtr->topIndex < 0) {
+		listPtr->topIndex = 0;
+	    }
+	}
     }
 
     /*
diff --git a/tests/listbox.test b/tests/listbox.test
index 3a20c07..886dfe1 100644
--- a/tests/listbox.test
+++ b/tests/listbox.test
@@ -6,7 +6,7 @@
 # Copyright (c) 1998-1999 by Scriptics Corporation.
 # All rights reserved.
 #
-# RCS: @(#) $Id: listbox.test,v 1.10 1999/11/24 00:20:14 ericm Exp $
+# RCS: @(#) $Id: listbox.test,v 1.11 1999/11/24 01:09:08 ericm Exp $
 
 if {[lsearch [namespace children] ::tcltest] == -1} {
     source [file join [pwd] [file dirname [info script]] defs.tcl]
@@ -1896,6 +1896,25 @@ test listbox-21.15 {ListboxListVarProc, update vertical scrollbar} {
     update
     set log
 } [list {y 0 1} {y 0 0.5}]
+test listbox-21.16 {ListboxListVarProc, update vertical scrollbar} {
+    catch {destroy .l}
+    catch {unset x}
+    listbox .l -listvar x -height 3
+    pack .l
+    update
+    set x [list 0 1 2 3 4 5]
+    .l yview scroll 3 units
+    update
+    set result {}
+    lappend result [.l yview]
+    set x [lreplace $x 3 3]
+    set x [lreplace $x 3 3]
+    set x [lreplace $x 3 3]
+    update
+    lappend result [.l yview]
+    set result
+} [list {0.5 1} {0 1}]
+
 # UpdateHScrollbar
 test listbox-22.1 {UpdateHScrollbar} {
     catch {destroy .l}