Added wxPopupWindow to GTK port, wxComboBox had to

be adapted a little but basically works not under
  GTK/Univ.
  I am pretty sure I forgot some file...


git-svn-id: https://svn.wxwidgets.org/svn/wx/wxWidgets/trunk@10887 c3d73ce0-8a6f-49c7-b76d-6d57e0e08775

src/univ/combobox.cpp

@@ -201,6 +201,8 @@ void wxComboControl::Init()
     m_popup = (wxComboPopup *)NULL;
     m_winPopup = (wxPopupComboWindow *)NULL;
     m_isPopupShown = FALSE;
+    m_btn = NULL;
+    m_text = NULL;
 }
 
 bool wxComboControl::Create(wxWindow *parent,
@@ -326,8 +328,11 @@ bool wxComboControl::Show(bool show)
     if ( !wxControl::Show(show) )
         return FALSE;
 
-    m_btn->Show(show);
-    m_text->Show(show);
+    if (m_btn)
+        m_btn->Show(show);
+    
+    if (m_text)
+        m_text->Show(show);
 
     return TRUE;
 }