Refactor: move wxComboBox::MSWDoPopupOrDismiss() down to wxChoice.

No real changes, just make this method available in wxChoice for the next
commit needs.

See #3113.

git-svn-id: https://svn.wxwidgets.org/svn/wx/wxWidgets/trunk@71103 c3d73ce0-8a6f-49c7-b76d-6d57e0e08775

include/wx/msw/choice.h

@@ -124,6 +124,9 @@ protected:
                            int width, int height,
                            int sizeFlags = wxSIZE_AUTO);
 
+    // Show or hide the popup part of the control.
+    void MSWDoPopupOrDismiss(bool show);
+
     // update the height of the drop down list to fit the number of items we
     // have (without changing the visible height)
     void MSWUpdateDropDownHeight();