Bug 125418 [Field Assist] - API - Should ContentProposalPopup be public?
In the initial release of the field assist API, the ContentProposalPopup is public. There's really no reason for this to be the case, as the popup is driven by the ContentProposalAdapter. The ContentProposalPopup should likely be made an inner type of the adapter.
bundles/org.eclipse.jface/src/org/eclipse/jface/fieldassist/ContentProposalAdapter.java
* @param proposalProvider
	 *            the <code>IContentProposalProvider</code> used to obtain
	 *            content proposals for this control, or <code>null</code> if
	 *            no content proposal is available.
	 * @param labelProvider
	 *            the label provider which provides text and image information
	 *            for content proposals. A <code>null</code> value indicates
	 *            that a default label provider is sufficient for any content
	 *            proposals that may occur.
	 * @param keyStroke
	 *            the keystroke that will invoke the content proposal popup. If
	 *            this value is <code>null</code>, then proposals will be
	 *            activated automatically when any of the auto activation
	 *            characters are typed.
	 * @param autoActivationCharacters
	 *            An array of characters that trigger auto-activation of content
	 *            proposal. If specified, these characters will trigger
	 *            auto-activation of the proposal popup, regardless of whether
	 *            an explicit invocation keyStroke was specified. If this
	 *            parameter is <code>null</code>, then only a specified
	 *            keyStroke will invoke content proposal. If this parameter is
	 *            <code>null</code> and the keyStroke parameter is
	 *            <code>null</code>, then all alphanumeric characters will
	 *            auto-activate content proposal.
	 * @param propagateKeys
	 *            a boolean that indicates whether key events (including
	 *            auto-activation characters) should be propagated to the
	 *            adapted control when the proposal popup is open.
	 * @param filterProposals
	 *            a boolean that indicates whether the proposal popup should