Bug 125955 [Field Assist] - StringIndexOutOfBoundsException when backspacing out of a filter
bundles/org.eclipse.jface/src/org/eclipse/jface/fieldassist/ContentProposalAdapter.java
* Indicates that a chosen proposal should be inserted into the field.
	 */
	public static final int PROPOSAL_INSERT = 1;
	/**
	 * Indicates that a chosen proposal should replace the entire contents of
	 * the field.
	 */
	public static final int PROPOSAL_REPLACE = 2;
	/**
	 * Indicates that the contents of the control should not be modified when a
	 * proposal is chosen. This is typically used when a client needs more
	 * specialized behavior when a proposal is chosen. In this case, clients
	 * typically register an IContentProposalListener so that they are notified
	 * when a proposal is chosen.
	 */
	public static final int PROPOSAL_IGNORE = 3;
	/*
	 * Set to <code>true</code> to use a Table with SWT.VIRTUAL. This is a
	 * workaround for https://bugs.eclipse.org/bugs/show_bug.cgi?id=98585#c40
	 * The corresponding SWT bug is
	 * https://bugs.eclipse.org/bugs/show_bug.cgi?id=90321
	 */
	private static final boolean USE_VIRTUAL = !"motif".equals(SWT.getPlatform()); 
	/*
	 * The delay before showing a secondary popup.
	 */
	private static final int POPUP_DELAY = 500;
	/*
	 * The character height hint for the popup.
	 */