Selecting a Row in a DataGrid

Question

Hello! I`ve a datagrid on a windows forms. Now i want to test online, which rows are selected. One possibility is to use DataGrid.Isselected(index) in the idle time. But there must be a better way. What i need is an event, like : OnselectingRow(), which is fired everytime, the user selects a new row. tnx for your helps.