Bug 256651 [FieldAssist] Wrong location calculation of proposal popup shell if content control is near bottom in the screen
bundles/org.eclipse.jface/src/org/eclipse/jface/fieldassist/ContentProposalAdapter.java
super(control.getShell(), SWT.RESIZE | SWT.ON_TOP, false, false, false,
					false, false, null, infoText);
			this.proposals = proposals;
		}
		/*
		 * (non-Javadoc)
		 * @see org.eclipse.jface.dialogs.PopupDialog#getForeground()
		 */
		protected Color getForeground() {
			return JFaceResources.getColorRegistry().get(
					JFacePreferences.CONTENT_ASSIST_FOREGROUND_COLOR);
		}
		
		/*
		 * (non-Javadoc)
		 * @see org.eclipse.jface.dialogs.PopupDialog#getBackground()
		 */
		protected Color getBackground() {
			return JFaceResources.getColorRegistry().get(
					JFacePreferences.CONTENT_ASSIST_BACKGROUND_COLOR);
		}
		/*
		 * Creates the content area for the proposal popup. This creates a table