Initialize picker style in native GTK file/dir pickers.

This fixes the styles used in the native wxGTK version after changes in
r63654: we must initialize base class m_pickerStyle now and the code didn't do
this before resulting in various asserts and incorrect behaviour.

git-svn-id: https://svn.wxwidgets.org/svn/wx/wxWidgets/trunk@63690 c3d73ce0-8a6f-49c7-b76d-6d57e0e08775

include/wx/gtk/filepicker.h

@@ -61,7 +61,7 @@ protected:                                                                    \
 class WXDLLIMPEXP_CORE wxFileButton : public wxGenericFileButton
 {
 public:
-    wxFileButton() { m_dialog = NULL; }
+    wxFileButton() { Init(); }
     wxFileButton(wxWindow *parent,
                  wxWindowID id,
                  const wxString& label = wxFilePickerWidgetLabel,
@@ -74,7 +74,8 @@ public:
                  const wxValidator& validator = wxDefaultValidator,
                  const wxString& name = wxFilePickerWidgetNameStr)
     {
-        m_dialog = NULL;
+        Init();
+        m_pickerStyle = style;
         Create(parent, id, label, path, message, wildcard,
                pos, size, style, validator, name);
     }
@@ -109,6 +110,10 @@ protected:
 
     wxDialog *m_dialog;
 
+private:
+    // common part of all ctors
+    void Init() { m_dialog = NULL; }
+
     DECLARE_DYNAMIC_CLASS(wxFileButton)
 };
 
@@ -134,6 +139,8 @@ public:
     {
         Init();
 
+        m_pickerStyle = style;
+
         Create(parent, id, label, path, message, wxEmptyString,
                 pos, size, style, validator, name);
     }