Bug 256651 [FieldAssist] Wrong location calculation of proposal popup shell if content control is near bottom in the screen
bundles/org.eclipse.jface/src/org/eclipse/jface/fieldassist/ContentProposalAdapter.java
private static final int POPUP_DELAY = 750;
	/*
	 * The character height hint for the popup. May be overridden by using
	 * setInitialPopupSize.
	 */
	private static final int POPUP_CHAR_HEIGHT = 10;
	/*
	 * The minimum pixel width for the popup. May be overridden by using
	 * setInitialPopupSize.
	 */
	private static final int POPUP_MINIMUM_WIDTH = 300;
	/*
	 * The pixel offset of the popup from the bottom corner of the control.
	 */
	private static final int POPUP_OFFSET = 3;
	/*
	 * Empty string.
	 */
	private static final String EMPTY = ""; 
	/*
	 * The object that provides content proposals.
	 */
	private IContentProposalProvider proposalProvider;
	/*
	 * A label provider used to display proposals in the popup, and to extract
	 * Strings from non-String proposals.
	 */
	private ILabelProvider labelProvider;
	/*
	 * The control for which content proposals are provided.