Colors, fonts ...

You can modify visual appearance of the grid using .active-controls-grid CSS selector.

.active-controls-grid {
    color: #ff0000;
    background: #6699cc;
    font-size: 8pt;
    font-weight: bold;
    border: 3px double #0099ff;
}

If you have several grids on one page - you can assign unique id to each of them

obj.setId("grid1");

and use this id as CSS selector:

#grid1 {
    height: 100px;
    background: #ddeeff;
}

#grid2 {
    height: 150px;
    background: #ddffee;
}