Clarify wxEVT_SLIDER event handler argument type in the documentation.

Unlike all other events generated by wxSlider, this one receives a
wxCommandEvent and not a wxScrollEvent.

Unfortunately @beginEventEmissionTable doesn't handle the case of a class
producing events of different types, perhaps it shouldn't be used at all here.

git-svn-id: https://svn.wxwidgets.org/svn/wx/wxWidgets/trunk@76720 c3d73ce0-8a6f-49c7-b76d-6d57e0e08775

interface/wx/slider.h

@@ -30,7 +30,10 @@
 
     On Windows, the track bar control is used.
 
-    Slider events are handled in the same way as a scrollbar.
+    Slider generates the same events as wxScrollBar but in practice the most
+    convenient way to process wxSlider updates is by handling the
+    slider-specific @c wxEVT_SLIDER event which carries wxCommandEvent
+    containing just the latest slider position.
 
     @beginStyleTable
     @style{wxSL_HORIZONTAL}
@@ -118,6 +121,8 @@
     @event{EVT_SLIDER(id, func)}
         Process @c wxEVT_SLIDER which is generated after any
         change of wxSlider position in addition to one of the events above.
+        Notice that the handler of this event receives a wxCommandEvent as
+        argument and not wxScrollEvent, as all the other handlers.
     @endEventTable
 
     @section slider_diff The difference between EVT_SCROLL_THUMBRELEASE and EVT_SCROLL_CHANGED