Generally, you do not need to call this method. It is automatically used by Lookup Property Editors to start the incremental search. Consider the following scenario. A Lookup Property Editor is selected but not activated:
Then an end-user presses the B key. The lookup dropdown is opened and the B character is passed to the Property Editor's StartIncrementalSearch method.
If the number of the objects in the data source collection bound to the current Property Editor is bigger than the IModelOptions.LookupSmallCollectionItemCount property value of the Application Model's IModelOptions node, the B character will be displayed in the search dialog:
Otherwise, the List Editor's control will start the incremental search using the B character as the first one: