Bug 265422 [FieldAssist] Field assist hint popup border is black
bundles/org.eclipse.jface/src/org/eclipse/jface/fieldassist/ControlDecoration.java
y = controlBounds.y;
		} else if ((position & SWT.BOTTOM) == SWT.BOTTOM) {
			y = controlBounds.y + control.getBounds().height
					- imageBounds.height;
		} else {
			
			y = controlBounds.y
					+ (control.getBounds().height - imageBounds.height) / 2;
		}
		
		Point globalPoint = control.getParent().toDisplay(x, y);
		Point targetPoint;
		if (targetControl == null) {
			targetPoint = globalPoint;
		} else {
			targetPoint = targetControl.toControl(globalPoint);
		}
		return new Rectangle(targetPoint.x, targetPoint.y, imageBounds.width,
				imageBounds.height);
	}
	/*
	 * Return true if the decoration should be shown, false if it should not.
	 */
	private boolean shouldShowDecoration() {
		if (!visible) {
			return false;
		}
		if (control == null || control.isDisposed() || getImage() == null) {
			return false;
		}