Generate the button clicks in GTK version of wxInfoBar.

Also add an example of handling info bar buttons events to the sample and
mention that this must be done using Connect() or by deriving from wxInfoBar
in the documentation.

git-svn-id: https://svn.wxwidgets.org/svn/wx/wxWidgets/trunk@62279 c3d73ce0-8a6f-49c7-b76d-6d57e0e08775

interface/wx/infobar.h

@@ -116,10 +116,20 @@ public:
         (in LTR layout), with each successive button being added to the right
         of the previous one.
 
-        Clicking the button will generate a normal event which can be handled
-        as usual. Notice that if you wish the info bar to be hidden when the
-        button is clicked, simply call @c event.Skip() in the button handler to
-        let the base class handler do it.
+        Clicking the button will generate a normal EVT_COMMAND_BUTTON_CLICKED
+        event which can be handled as usual. The default handler in wxInfoBar
+        itself closes the window whenever a button in it is clicked so if you
+        wish the info bar to be hidden when the button is clicked, simply call
+        @c event.Skip() in the button handler to let the base class handler do
+        it. On the other hand, if you don't skip the event, the info bar will
+        remain opened so make sure to do it for at least some buttons to allow
+        the user to close it.
+
+        Notice that the generic wxInfoBar implementation handles the button
+        events itself and so they are not propagated to the info bar parent and
+        you need to either inherit from wxInfoBar and handle them in your
+        derived class or use wxEvtHandler::Connect(), as is done in the dialogs
+        sample, to handle the button events in the parent frame.
 
         @param btnid
             Id of the button. It will be used in the button message clicking