Document and test wxDatePickerCtrl::SetRange() date-clamping behaviour.

Document that the current value of the control is adjusted if it doesn't lie
in the newly set range and add a unit test to check for this, now that it
actually passes under all platforms, after the previous commits.

interface/wx/datectrl.h

@@ -173,6 +173,10 @@ public:
         becomes the earliest date (inclusive) accepted by the control. If
         @a dt2 is valid, it becomes the latest possible date.
 
+        Notice that if the current value is not inside the new range, it will
+        be adjusted to lie inside it, i.e. calling this method can change the
+        control value, however no events are generated by it.
+
         @remarks If the current value of the control is outside of the newly
                  set range bounds, the behaviour is undefined.
     */

tests/controls/datepickerctrltest.cpp

@@ -106,6 +106,13 @@ void DatePickerCtrlTestCase::Range()
 
     m_datepicker->SetValue(dtStart - wxTimeSpan::Day());
     CPPUNIT_ASSERT_EQUAL( dtEnd, m_datepicker->GetValue() );
+
+
+    // Changing the range should clamp the current value to it if necessary.
+    const wxDateTime
+        dtBeforeEnd = dtEnd - wxDateSpan::Day();
+    m_datepicker->SetRange(dtStart, dtBeforeEnd);
+    CPPUNIT_ASSERT_EQUAL( dtBeforeEnd, m_datepicker->GetValue() );
 }
 
 #endif // wxUSE_DATEPICKCTRL