Use a panel in internat sample to make it look better under MSW

Creating the controls directly on wxFrame is not recommended and looks
ugly under MSW due to the wrong background being used, so add an
intermediate panel.

samples/internat/internat.cpp

@@ -378,16 +378,18 @@ MyFrame::MyFrame(wxLocale& locale)
     // this demonstrates RTL support in wxStatusBar:
     CreateStatusBar(1);
 
+    wxPanel* const panel = new wxPanel(this);
+
     // create some controls affected by the locale
     wxSizer* const topSizer = new wxBoxSizer(wxVERTICAL);
 
     // this demonstrates RTL layout mirroring for Arabic locales and using
     // locale-specific decimal separator in wxSpinCtrlDouble.
     wxSizer *sizer = new wxBoxSizer(wxHORIZONTAL);
-    sizer->Add(new wxStaticText(this, wxID_ANY, _("Numeric input:")),
+    sizer->Add(new wxStaticText(panel, wxID_ANY, _("Numeric input:")),
                wxSizerFlags().Center().Border());
 
-    wxSpinCtrlDouble* const spin = new wxSpinCtrlDouble(this, wxID_ANY);
+    wxSpinCtrlDouble* const spin = new wxSpinCtrlDouble(panel, wxID_ANY);
     spin->SetDigits(2);
     spin->SetValue(12.34);
     sizer->Add(spin, wxSizerFlags().Center().Border());
@@ -395,7 +397,7 @@ MyFrame::MyFrame(wxLocale& locale)
     topSizer->Add(sizer, wxSizerFlags().Center());
 
     // show that week days and months names are translated too
-    topSizer->Add(new wxCalendarCtrl(this, wxID_ANY),
+    topSizer->Add(new wxCalendarCtrl(panel, wxID_ANY),
                   wxSizerFlags().Center().Border());
 
     // show the difference between wxString::Format() and wxNumberFormatter:
@@ -403,7 +405,7 @@ MyFrame::MyFrame(wxLocale& locale)
     // locale
     topSizer->Add(new wxStaticText
                       (
-                        this,
+                        panel,
                         wxID_ANY,
                         wxString::Format
                         (
@@ -414,7 +416,8 @@ MyFrame::MyFrame(wxLocale& locale)
                       ),
                   wxSizerFlags().Center().Border());
 
-    SetSizerAndFit(topSizer);
+    panel->SetSizer(topSizer);
+    topSizer->SetSizeHints(this);
 }
 
 void MyFrame::OnQuit(wxCommandEvent& WXUNUSED(event) )