Document how to get the previous selection in wxEVT_GRID_SELECT_CELL handler.

Make explicit the fact that the cell coordinates in the event are the
coordinates of the newly selected cell and that the previously selected one is
available from wxGrid itself.

git-svn-id: https://svn.wxwidgets.org/svn/wx/wxWidgets/trunk@66496 c3d73ce0-8a6f-49c7-b76d-6d57e0e08775

interface/wx/grid.h

@@ -4251,6 +4251,10 @@ public:
 
     /**
         Column at which the event occurred.
+
+        Notice that for a @c wxEVT_GRID_SELECT_CELL event this column is the
+        column of the newly selected cell while the previously selected cell
+        can be retrieved using wxGrid::GetGridCursorCol().
     */
     virtual int GetCol();
 
@@ -4261,6 +4265,10 @@ public:
 
     /**
         Row at which the event occurred.
+
+        Notice that for a @c wxEVT_GRID_SELECT_CELL event this row is the row
+        of the newly selected cell while the previously selected cell can be
+        retrieved using wxGrid::GetGridCursorRow().
     */
     virtual int GetRow();