By default, RadGridView starts editing a cell when clicking on a current row. So, you should first make the row current by single click, and clicking a second time on the same row will start the editing process. It is possible to follow the whole editing lifecycle via the useful events that RadGridView offers:
1. EditorRequired - the first event that triggers when an editing operation is about to start. The GridViewEditManager asks for the default editor, relevant for this particular column. The EditorRequiredEventArgs gives you access to the default EditorType. This is the appropriate place to replace the default editor with another default or custom editor. It is necessary to set the either the EditorType or the Editor property in the event arguments.
2. CellBeginEdit - The GridViewCellCancelEventArgs allows you to cancel the edit operation by setting the Cancel argument to true. Thus, considering the row/column and row index/ column index, it is possible to restrict entering edit mode in certain cases.
3. CellEditorInitialized - fires when the editor is already activated and initialized. It is the appropriate place to apply any changes to the editor and adjust any property settings. The GridViewCellEventArgs gives you access to the ActiveEditor and the initial Value.
4. ValueChanging - fires while the editor is being active and the editor's value is changing. The ValueChangingEventArgs gives you access to the OldValue and NewValue. It is possible to restrict the newly entered value by setting the Cancel argument to true.
5. ValueChanged - fires while the editor is being active and the editor's value is changed. This new value is not committed to underlying cell yet. It is available only in the editor.
6. CellValueChanged - The GridViewEditManager confirms the editor's changes when the user presses Enter/Tab or navigate to another cell. Thus, the new editor's value is committed to the cell and the cell's value is changed accordingly.
7. CellEndEdit - The GridViewEditManager ends the edit operation and deactivates the editor when the editor's value is either confirmed by pressing Enter/Tab or the user discards the changes by pressing Escape.
When the grid is in edit mode and the user navigates to another cell either by pressing Tab or by clicking a cell, the editor will be activated for the new current cell (if the BeginEditMode property value is not BeginEditProgrammatically).