Document that wxComboBox::Dismiss() and Popup() generate events.

Currently these functions generate events in both of the existing
implementations (GTK and MSW) so it is simpler to let them to continue to do
it but this must at least be documented as this is probably unexpected by
users.

git-svn-id: https://svn.wxwidgets.org/svn/wx/wxWidgets/trunk@63247 c3d73ce0-8a6f-49c7-b76d-6d57e0e08775

interface/wx/combobox.h

@@ -249,6 +249,9 @@ public:
 
         Currently only implemented in wxMSW and wxGTK.
 
+        Notice that calling this function will generate a
+        wxEVT_COMMAND_COMBOBOX_DROPDOWN event.
+
         @since 2.9.1
     */
     virtual void Popup();
@@ -258,6 +261,9 @@ public:
 
         Currently only implemented in wxMSW and wxGTK.
 
+        Notice that calling this function will generate a
+        wxEVT_COMMAND_COMBOBOX_CLOSEUP event.
+
         @since 2.9.1
     */
     virtual void Dismiss();