Hi Abby,
Thanks for your interest in Syncfusion Products.
Please refer to the following sample in which the checkbox is also displayed in Column header which provides CheckAll functionality(i.e., once it is checked, all cells in that column get checked). Event like TableControlCellClick, TableControl.MouseUp, TableControlCheckBoxClick, SaveCellText are handled to effectively achieve this functionality.
http://files.syncfusion.com/support/Grid.Windows/F82373.zipRegards,
Rajadurai