The current version of iGrid does not allow you to have the check box control and text in the same cell (also true for group rows). If you need to implement the functionality like this, you need to imitate it with cell image. Use a custom-drawn check box as the cell image, and tick/untick it when the user clicks it.
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As for this limitation in general, we already received many suggestions to implement check boxes for normal cells. Most likely, we'll abandon the current approach to cell types in the future versions of iGrid.NET when we should set the cell type - either normal "text" cell (default) or check box cell - as we did it a couple of years ago for combo box cells. In the previous versions of iGrid, we needed to specify a special combo box cell type, but now you just need to attach a drop-down list to normal cell to make it combo box cell. We are planning to do the same for check box cells: you will have an option (flag) you can set to ADD the check box control to normal cells, and every cell will have an additional property of say the .NET CheckState enumeration type you can use to know the state of the check box in the cell.