Bug 148357 [Field Assist] - API - provide access for closing the proposal popup
I think that the field assist API needs more hooks to be customizable. For example : 1) There is no way to manually close/open the popup. Most of the times, this is the easier thing for a user to ask to implement his custom behaviour. 2) There is no way to intercept keystrokes/events directed to the field. 3) There is no way to control focus.
bundles/org.eclipse.jface/src/org/eclipse/jface/fieldassist/ContentProposalAdapter.java
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);
						asyncRecomputeProposals(filterText);
						return;
					}