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
*            the number of pixels that should be reserved between the
	 *            horizontal edge of the control and the adjacent edge of the
	 *            decoration.
	 */
	public void setMarginWidth(int marginWidth) {
		this.marginWidth = marginWidth;
		update();
	}
	/**
	 * Something has changed, requiring redraw. Redraw the decoration and update
	 * the hover text if appropriate.
	 */
	protected void update() {
		if (control == null) {
			return;
		}
		Rectangle rect = getDecorationRectangle(control.getShell());
		
		control.getShell()
				.redraw(rect.x, rect.y, rect.width, rect.height, true);
		control.getShell().update();
		if (hover != null && getDescriptionText() != null) {
			hover.setText(getDescriptionText(), getDecorationRectangle(control
					.getParent()), control);
		}
	}
	/*
	 * Show the specified text in the hover, positioning the hover near the
	 * specified control.
	 */