Bug 163360 [Field Assist] - API - Provide ControlDecoration constructor without specifying decoration
Currently you can only create a ControlDecoration by specifying the control and the decoration in the constructor. This works nicely when the decoration is static (ie, always content assist). But there are use cases where the decoration changes depending on the state of the field, and at creation time, it's not clear which decoration will be set. Having a constructor that doesn't require a decoration would be nice.
bundles/org.eclipse.jface/src/org/eclipse/jface/fieldassist/ControlDecoration.java
return e;
		}
		/*
		 * Compute a new shape for the hover shell.
		 */
		void setNewShape() {
			Region oldRegion = region;
			region = new Region();
			region.add(getPolygon(false));
			hoverShell.setRegion(region);
			if (oldRegion != null) {
				oldRegion.dispose();
			}
		}
	}
	/**
	 * Construct a ControlDecoration for the specified control, with the
	 * specified decoration and position.
	 * <p>
	 * SWT constants are used to specify the position of the decoration relative
	 * to the control. The position should include style bits describing both
	 * the vertical and horizontal orientation. <code>SWT.LEFT</code> and
	 * <code>SWT.RIGHT</code> describe the horizontal placement of the
	 * decoration relative to the control, and the constants
	 * <code>SWT.TOP</code>, <code>SWT.CENTER</code>, and
	 * <code>SWT.BOTTOM</code> describe the vertical alignment of the
	 * decoration relative to the control. Decorations always appear on either
	 * the left or right side of the control, never above or below it. For
	 * example, a decoration appearing on the left side of the field, at the
	 * top, is specified as SWT.LEFT | SWT.TOP. If no position style bits are