How to refresh the grid, not render it again.

[Sirth]

Hi,
I'm creating a grid which is stored in a global object.
The grid is rendered in a div inside a tab panel.
after changing from tab to tab, and coming back again to the grid, I need to mouseover it in order to turn it visible again.
I wonder if there's a way like
myGrid.refresh();
is useless to call myGrid.render();
Because everything is already in memory.
Any Idea ?