Bug 132039 [Field Assist] - secondary popup should update on same delay as its invocation delay
bundles/org.eclipse.jface/src/org/eclipse/jface/fieldassist/ContentProposalAdapter.java
switch (key) {
				case SWT.ESC: 
					e.doit = false;
					close();
					break;
				case SWT.LF:
				case SWT.CR:
					e.doit = false;
					Object p = getSelectedProposal();
					if (p != null) {
						acceptCurrentProposal();
					}
					close();
					break;
				case SWT.TAB:
					e.doit = false;
					getShell().setFocus();
					return;
				case SWT.BS:
					
					if (filterStyle != FILTER_NONE) {
						
						if (filterText.length() == 0) {
							return;
						}
						
						filterText = filterText.substring(0, filterText
								.length() - 1);
					}