Javadoc
Set the integer style that indicates how keystrokes affect the content of
the proposal popup while it is open. Popup-based filtering is useful for
narrowing and navigating the list of proposals provided once the popup is
open. Filtering of the proposals will occur even when the control content
is not affected by user typing. Note that automatic filtering is not used
to achieve content-sensitive filtering such as auto-completion. Filtering
that is sensitive to changes in the control content should be performed
by the supplied
IContentProposalProvider.