Use border style consistently in the widgets sample

Use GetAttrs().m_defaultFlags everywhere when creating the widgets, it
was done for some but not all of them before, without any apparent
reason.

This should make setting various border styles work (for the widgets
supporting them).

samples/widgets/datepick.cpp

@@ -243,7 +243,7 @@ void DatePickerWidgetsPage::CreateDatePicker()
 
     delete m_datePicker;
 
-    long style = 0;
+    long style = GetAttrs().m_defaultFlags;
     switch ( m_radioKind->GetSelection() )
     {
         case 0: