Bug 295981 [Forms] FormImages & FormFonts are not disposed correctly
tests/org.eclipse.ui.tests.forms/forms/org/eclipse/ui/tests/forms/util/FormImagesTests.java
kit1.getColors().createColor(blueKey, new RGB(0,0,255));
		kit1.getColors().createColor(redKey, new RGB(255,0,0));
		FormToolkit kit2 = new FormToolkit(display);
		kit2.getColors().createColor(blueKey, new RGB(0,0,255));
		kit2.getColors().createColor(redKey, new RGB(255,0,0));
		Image image1 = FormImages.getInstance().getGradient(kit1.getColors().getColor(blueKey), kit1.getColors().getColor(redKey), 21, 21, 0);
		Image image2 = FormImages.getInstance().getGradient(kit2.getColors().getColor(blueKey), kit2.getColors().getColor(redKey), 21, 21, 0);
		Assert.assertEquals("different images were created for the same RGBs with different Color instances", image1, image2);
		Image image3 = FormImages.getInstance().getGradient(new Color(display,0,0,255), new Color(display,255,0,0), 21, 21, 0);
		Assert.assertEquals("different images were created for the same RGBs with different Color instances", image1, image3);
		kit1.dispose();
		Assert.assertFalse("image was disposed after toolkits were disposed", image1.isDisposed());
		kit2.dispose();
		Assert.assertFalse("image was disposed after toolkits were disposed", image2.isDisposed());
		FormImages.getInstance().markFinished(image1);
		Assert.assertFalse("image was disposed early", image1.isDisposed());
		FormImages.getInstance().markFinished(image2);
		Assert.assertFalse("image was disposed early", image2.isDisposed());
		FormImages.getInstance().markFinished(image3);
		Assert.assertTrue("image was not disposed", image3.isDisposed());
	}
	
	public void testDisposeUnknown() {
		Display display = Display.getCurrent();
		Image image = new Image(display, 10, 10);
		FormImages.getInstance().markFinished(image);
		Assert.assertTrue("markFinished(...) did not dispose of an unknown image", image.isDisposed());
	}
}