Applications cannot call this protected method. Data-aware grids call EndLayout internally after changes to the Columns property or the dataset. EndLayout decrements the LayoutLock property which was previously incremented by BeginLayout before the Columns property was changed or when notification of the change to the dataset was received. 

If LayoutLock returns to 0, EndLayout updates the Fields property to match both the bindings of the Columns property and the fields available in the dataset. The Columns property is then updated in turn to match the Fields property. This ensures that the Columns property matches both the specified column bindings and the fields available in the dataset. 

BeginLayout 

Columns 

DefineFieldMap 

Fields 

LayoutLock