Bug 132101 [Field Assist] does not work for characters that need AltGr, Ctrl+Alt or Strg+Alt
bundles/org.eclipse.jface/src/org/eclipse/jface/fieldassist/ContentProposalAdapter.java
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);
					break;
				default:
					
					
					
					if (Character.isDefined(key)) {
						if (filterStyle == FILTER_CUMULATIVE) {
							filterText = filterText + String.valueOf(key);
						} else if (filterStyle == FILTER_CHARACTER) {