Refresh window layout after changing wxSpinCtrl base in widgets sample

Changing the base of the number changes the size of wxSpinCtrl
so the layout needs to be reset to account this new size.

samples/widgets/spinbtn.cpp

@@ -480,6 +480,8 @@ void SpinBtnWidgetsPage::OnButtonSetBase(wxCommandEvent& WXUNUSED(event))
     {
         wxLogWarning("Setting base %d failed.", m_base);
     }
+
+    m_sizerSpin->Layout();
 }
 
 void SpinBtnWidgetsPage::OnButtonSetValue(wxCommandEvent& WXUNUSED(event))