vertical scrollbar hidden after refresh

Hi,
I want to update my datagrid and after the refresh() the
vertical scrollbar is hidden.

At first I clear the grid:
grid.clearCellModel();
grid.clearRowModel();
grid.clearScrollModel();
grid.clearSelectionModel();
grid.clearSortModel();

then I build a new array and sets the data to the grid. (setCellData())

At last I refresh the grid and the vertical scrollbar is hidden.

http://www.activewidgets.com/aw.ui.grid/selected-model.html
so use : grid.clearSelectedModel();
instead of : grid.clearSelectionModel();

http://www.activewidgets.com/javascript.forum.25468.7/horizontal-scrollbar-not-showing-when.html