add const qualifiers

git-svn-id: https://svn.wxwidgets.org/svn/wx/wxWidgets/trunk@52414 c3d73ce0-8a6f-49c7-b76d-6d57e0e08775

interface/scrolbar.h

@@ -88,28 +88,28 @@ public:
         
         @see SetScrollbar()
     */
-    int GetPageSize();
+    int GetPageSize() const;
 
     /**
         Returns the length of the scrollbar.
         
         @see SetScrollbar()
     */
-    int GetRange();
+    int GetRange() const;
 
     /**
         Returns the current position of the scrollbar thumb.
         
         @see SetThumbPosition()
     */
-    int GetThumbPosition();
+    int GetThumbPosition() const;
 
     /**
         Returns the thumb or 'view' size.
         
         @see SetScrollbar()
     */
-    int GetThumbSize();
+    int GetThumbSize() const;
 
     /**
         Sets the scrollbar properties.