Add wxComboBox::Popup() and Dismiss() to manually show or hide its popup.

Add implementations for wxMSW and wxGTK.

Closes #11506.

git-svn-id: https://svn.wxwidgets.org/svn/wx/wxWidgets/trunk@63242 c3d73ce0-8a6f-49c7-b76d-6d57e0e08775

interface/wx/combobox.h

@@ -243,5 +243,23 @@ public:
             The text to set.
     */
     virtual void SetValue(const wxString& text);
+
+    /**
+        Shows the list box portion of the combo box.
+
+        Currently only implemented in wxMSW and wxGTK.
+
+        @since 2.9.1
+    */
+    virtual void Popup();
+
+    /**
+        Hides the list box portion of the combo box.
+
+        Currently only implemented in wxMSW and wxGTK.
+
+        @since 2.9.1
+    */
+    virtual void Dismiss();
 };