Bug 125955 [Field Assist] - StringIndexOutOfBoundsException when backspacing out of a filter
bundles/org.eclipse.jface/src/org/eclipse/jface/fieldassist/ContentProposalAdapter.java
break;
				case SWT.TAB:
					e.doit = false;
					getShell().setFocus();
					return;
				case SWT.BS:
					
					if (filter) {
						filterText = filterText.substring(0, filterText
								.length() - 1);
						recomputeProposals(filterText);
						return;
					}
				default:
					
					
					
					
					if (filter && Character.isDefined(key)) {
						filterText = filterText + String.valueOf(key);
						recomputeProposals(filterText);
					}
					break;
				}
			}
		}
		/*
		 * Internal class used to implement the secondary popup.
		 */
		private class InfoPopupDialog extends PopupDialog {