Point computeSize(Control control, int wHint, int hHint, boolean flushCache) {
		if (flushCache)
			flushCache();
		if (wHint == SWT.DEFAULT && hHint == SWT.DEFAULT) {
			if (defaultWidth == -1 || defaultHeight == -1) {
				Point size = control.computeSize(wHint, hHint, flushCache);
				defaultWidth = size.x;
				defaultHeight = size.y;
			}
			return new Point(defaultWidth, defaultHeight);
		}
		if (currentWidth == -1 || currentHeight == -1 || wHint != currentWhint
				|| hHint != currentHhint) {
			Point size = control.computeSize(wHint, hHint, flushCache);
			currentWhint = wHint;
			currentHhint = hHint;
			currentWidth = size.x;
			currentHeight = size.y;
		}
		return new Point(currentWidth, currentHeight);
	}