Fixed bug [841280] - spinbox -from and -to defaults and behaviour

3 files changed, 28 insertions, 9 deletions

diff --git a/doc/spinbox.n b/doc/spinbox.n
index 330bb17..e030aa3 100644
--- a/doc/spinbox.n
+++ b/doc/spinbox.n
@@ -54,7 +54,8 @@ as it will format a floating-point number.
 A floating-point value corresponding to the lowest value for a spinbox, to
 be used in conjunction with \fB\-to\fR and \fB\-increment\fR.  When all
 are specified correctly, the spinbox will use these values to control its
-contents.  This value must be less than the \fB\-to\fR option.
+contents. If this value is greater than the \fB\-to\fR option, then
+\fB\-from\fR and \fB\-to\fR values are automatically swapped.
 If \fB\-values\fR is specified, it supersedes this option.
 .OP "\-invalidcommand or \-invcmd" invalidCommand InvalidCommand
 Specifies a script to eval when \fB\-validatecommand\fR returns 0.  Setting
@@ -83,7 +84,8 @@ be displayed in a different color, depending on the values of the
 A floating-point value corresponding to the highest value for the spinbox,
 to be used in conjunction with \fB\-from\fR and \fB\-increment\fR.  When
 all are specified correctly, the spinbox will use these values to control
-its contents.  This value must be greater than the \fB\-from\fR option.
+its contents. If this value is less than the \fB\-from\fR option, then
+\fB\-from\fR and \fB\-to\fR values are automatically swapped.
 If \fB\-values\fR is specified, it supersedes this option.
 .OP \-validate validate Validate
 Specifies the mode in which validation should operate: \fBnone\fR,
diff --git a/generic/tkEntry.c b/generic/tkEntry.c
index ea8d7f1..5681e47 100644
--- a/generic/tkEntry.c
+++ b/generic/tkEntry.c
@@ -1176,13 +1176,15 @@ ConfigureEntry(
 
 	if (entryPtr->type == TK_SPINBOX) {
 	    if (sbPtr->fromValue > sbPtr->toValue) {
-		Tcl_SetObjResult(interp, Tcl_NewStringObj(
-			"-to value must be greater than -from value",
-			-1));
-		Tcl_SetErrorCode(interp, "TK", "SPINBOX", "RANGE_SANITY",
-			NULL);
-		continue;
-	    }
+                /*
+                 * Swap -from and -to values.
+                 */
+
+                double tmpFromTo = sbPtr->fromValue;
+
+                sbPtr->fromValue = sbPtr->toValue;
+                sbPtr->toValue = tmpFromTo;
+            }
 
 	    if (sbPtr->reqFormat && (oldFormat != sbPtr->reqFormat)) {
 		/*
diff --git a/tests/spinbox.test b/tests/spinbox.test
index 594cc90..0264b77 100644
--- a/tests/spinbox.test
+++ b/tests/spinbox.test
@@ -2072,6 +2072,21 @@ test spinbox-5.11 {ConfigureSpinbox procedure} -setup {
 } -cleanup {
     destroy .e
 } -result {}
+test spinbox-5.12 {ConfigureSpinbox procedure, -from and -to swapping} -setup {
+    spinbox .e
+} -body {
+    # this statement used to trigger error "-to value must be greater than -from value"
+    # because default value for -to is zero (bug [841280ffff])
+    set res [catch {.e configure -from 10}]
+    .e configure -from 1971 -to 2016  ; # standard case
+    lappend res [.e cget -from] [.e cget -to]
+    .e configure -from 2016 -to 1971  ; # auto-swapping happens
+    lappend res [.e cget -from] [.e cget -to]
+    .e configure -to 1971 -from 2016 ; # auto-swapping, order of options does not matter
+    lappend res [.e cget -from] [.e cget -to]
+} -cleanup {
+    destroy .e
+} -result {0 1971.0 2016.0 1971.0 2016.0 1971.0 2016.0}
 
 # No tests for DisplaySpinbox.