Bug 139063 [Field Assist] - API - behavior of text insert not taking selection into account
Field Assist Example - set acceptance style to "Insert into field content" - type some text into the text and combo - select a subset of the text and invoke content assist - choose a proposal in the popup outcome: text is inserted at the insertion point expected: text should be inserted, but should replace any selected text Is this a regression?
bundles/org.eclipse.jface/src/org/eclipse/jface/fieldassist/ContentProposalAdapter.java
* need to remember it.
	 */
	private int insertionPos = -1;
	/*
	 * A flag that indicates that a pending modify event was caused by the
	 * adapter rather than the user.
	 */
	private boolean modifyingControlContent = false;
	/**
	 * Construct a content proposal adapter that can assist the user with
	 * choosing content for the field.
	 * 
	 * @param control
	 *            the control for which the adapter is providing content assist.
	 *            May not be <code>null</code>.
	 * @param controlContentAdapter
	 *            the <code>IControlContentAdapter</code> used to obtain and
	 *            update the control's contents as proposals are accepted. May
	 *            not be <code>null</code>.
	 * @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 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