Hello,

There is a "Title" property in each colunm definition (in Header) -- this is actually the tooltip that is displayed for the header on mouseover.

                <igtbl:UltraGridColumn BaseColumnName="FirstName" IsBound="True"
                        Key="FirstName">
                        <Header Caption="FirstName" Title="ToolTip">
                            <RowLayoutColumnInfo OriginX="2" />
                        </Header>
                        <Footer>
                            <RowLayoutColumnInfo OriginX="2" />
                        </Footer>
                    </igtbl:UltraGridColumn>

HTH,