user32/listbox: Use a helper function to check the selection state of an item.

dlls/user32/listbox.c

@@ -120,6 +120,11 @@ static TIMER_DIRECTION LISTBOX_Timer = LB_TIMER_NONE;
 
 static LRESULT LISTBOX_GetItemRect( const LB_DESCR *descr, INT index, RECT *rect );
 
+static BOOL is_item_selected( const LB_DESCR *descr, UINT index )
+{
+    return descr->items[index].selected;
+}
+
 /*********************************************************************
  * listbox class descriptor
  */
@@ -2866,7 +2871,7 @@ LRESULT ListBoxWndProc_common( HWND hwnd, UINT msg, WPARAM wParam, LPARAM lParam
     case LB_GETSEL:
         if (((INT)wParam < 0) || ((INT)wParam >= descr->nb_items))
             return LB_ERR;
-        return descr->items[wParam].selected;
+        return is_item_selected(descr, wParam);
 
     case LB_SETSEL:
         ret = LISTBOX_SetSelection( descr, lParam, wParam, FALSE );