Edited Issue: EFDesigner - small UI tweaks to make the designer consistent with VS solution explorer [653]

Expanders in Win8's new theme should look like triangles and not +/- signs <br />Removing unnecessary spacing on the left of first item (in alignment with Solution Explorer)<br />Related items:<br /> - Aero.NormalColor.xaml should be moved out of XmlCore(http://entityframework.codeplex.com/workitem/321) <br /> - [UX] Model Browser: Tree triangles inconsistent with Solution Explorer (http://entityframework.codeplex.com/workitem/331 )<br />