Bug 170827 ControlDecoration uses the wrong GC method to render text
The constructor of the Hover in ControlDecoration: hoverShell.addPaintListener(new PaintListener() { public void paintControl(PaintEvent pe) { pe.gc.drawString(text, hm, hm); if (!CARBON) { pe.gc.drawPolygon(getPolygon(true)); } } }); The size of the hover is correctly performed when there are carriage returns in the text. However, the text is painted as String. This causes only the first line to be painted and the rest of the hover is empty. The fix is to use GC.drawText' instead.
bundles/org.eclipse.jface/src/org/eclipse/jface/fieldassist/ControlDecoration.java
if (control == null || control.isDisposed() || getImage() == null) {
			return false;
		}
		if (showOnlyOnFocus) {
			return hasFocus;
		}
		return true;
	}
	/*
	 * If in debug mode, print info about adding the specified listener.
	 */
	private void printAddListener(Widget widget, String listenerType) {
		listenerInstalls++;
		if (DEBUG) {
			System.out
					.println("Added listener>>>" + listenerType + " to>>>" + widget); 
		}
	}
	/*
	 * If in debug mode, print info about adding the specified listener.
	 */
	private void printRemoveListener(Widget widget, String listenerType) {
		listenerInstalls--;
		if (DEBUG) {
			System.out
					.println("Removed listener>>>" + listenerType + " from>>>" + widget); 
		}
	}
}