Add support for custom comboboxes in wxFileDialogCustomize

Allow using simple (i.e. not editable) comboboxes, known as wxChoice in
wx API, in the dialog too.

Demonstrate their use in the dialogs sample.

include/wx/filedlgcustomize.h

@@ -16,6 +16,7 @@ class wxFileDialogCustomControlImpl;
 class wxFileDialogButtonImpl;
 class wxFileDialogCheckBoxImpl;
 class wxFileDialogRadioButtonImpl;
+class wxFileDialogChoiceImpl;
 class wxFileDialogTextCtrlImpl;
 class wxFileDialogStaticTextImpl;
 class wxFileDialogCustomizeImpl;
@@ -110,6 +111,25 @@ private:
     wxDECLARE_NO_COPY_CLASS(wxFileDialogRadioButton);
 };
 
+// A class representing a custom combobox button.
+class WXDLLIMPEXP_CORE wxFileDialogChoice : public wxFileDialogCustomControl
+{
+public:
+    int GetSelection() const;
+    void SetSelection(int n);
+
+    // Ctor is only used by wxWidgets itself.
+    explicit wxFileDialogChoice(wxFileDialogChoiceImpl* impl);
+
+protected:
+    virtual bool OnDynamicBind(wxDynamicEventTableEntry& entry) wxOVERRIDE;
+
+private:
+    wxFileDialogChoiceImpl* GetImpl() const;
+
+    wxDECLARE_NO_COPY_CLASS(wxFileDialogChoice);
+};
+
 // A class representing a custom text control.
 class WXDLLIMPEXP_CORE wxFileDialogTextCtrl : public wxFileDialogCustomControl
 {
@@ -151,6 +171,7 @@ public:
     wxFileDialogButton* AddButton(const wxString& label);
     wxFileDialogCheckBox* AddCheckBox(const wxString& label);
     wxFileDialogRadioButton* AddRadioButton(const wxString& label);
+    wxFileDialogChoice* AddChoice(size_t n, const wxString* strings);
     wxFileDialogTextCtrl* AddTextCtrl(const wxString& label = wxString());
     wxFileDialogStaticText* AddStaticText(const wxString& label);
 

include/wx/private/filedlgcustomize.h

@@ -45,6 +45,13 @@ public:
     virtual void SetValue(bool value) = 0;
 };
 
+class wxFileDialogChoiceImpl : public wxFileDialogCustomControlImpl
+{
+public:
+    virtual int GetSelection() = 0;
+    virtual void SetSelection(int n) = 0;
+};
+
 class wxFileDialogTextCtrlImpl : public wxFileDialogCustomControlImpl
 {
 public:
@@ -68,6 +75,7 @@ public:
     virtual wxFileDialogButtonImpl* AddButton(const wxString& label) = 0;
     virtual wxFileDialogCheckBoxImpl* AddCheckBox(const wxString& label) = 0;
     virtual wxFileDialogRadioButtonImpl* AddRadioButton(const wxString& label) = 0;
+    virtual wxFileDialogChoiceImpl* AddChoice(size_t n, const wxString* strings) = 0;
     virtual wxFileDialogTextCtrlImpl* AddTextCtrl(const wxString& label) = 0;
     virtual wxFileDialogStaticTextImpl* AddStaticText(const wxString& label) = 0;