Hello Arseny,

In order to manipulate the styles you could modify the css files, located in the ig_res folder:

If I understand your requirement correctly, your goal is to manipulate the elements borders so separation lines between row/columns are displayed. The CSS files, responsible for the stilling of the Infragistics Controls could be found in the ig_res folder, that is created when an Infragistics Control is initially added.

For modifying the lines you could access these css files, located in ig_dataGrid.css:
tbody.igg_ItemIE6 tr td AND tbody.igg_Item>tr>td

You could modify the way the text in cells is displayed by choosing white-space property, like:
white-space: nowrap;

tbody.igg_ItemIE6 tr td
{  
border-top:solid 1px #D8D8D8;  
white-space:nowrap;
}

tbody.igg_Item>tr>td
{  
border-top:solid 1px #D8D8D8;  
white-space:nowrap;
}

.igg_RowSelector
{
border-top:solid 1px #D8D8D8;  
border-right:solid 1px #D8D8D8;  
border-left:solid 1px #D8D8D8;
}

If you continue to experience any issues please do not hesitate to contact me.

I believe this has being discused in the following forum thread:
http://ko.infragistics.com/community/forums/t/92645.aspx