Bug 132798 [Field Assist] - Pressing Backspace at offset 0 should not reload field assist popup
N20060322-0010. After migrating the Find/Replace dialog to the new field assist support I found the following blooper: pressing the Backspace key at offset 0 reloads the field assist popup. Test Case: 1. in a text editor press Ctrl+F 2. enable regex search 3. in the Find filed press Ctrl+Space 4. continuously press Backspace ==> each time the proposal list is reloaded.
bundles/org.eclipse.jface/src/org/eclipse/jface/fieldassist/ContentProposalAdapter.java
*/
	private static final boolean USE_VIRTUAL = !"motif".equals(SWT.getPlatform()); 
	/*
	 * The delay before showing a secondary popup.
	 */
	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