IE: test_Button button style gets stuck on dragOut

[haysmark]

In IE7:

1. Open test_Button
2. Click a button, and drag your mouse out of the button
3. The "pressed" style gets partially stuck

For example, if you drag out of the custom styled buttons on the bottom, the text in the button remains blue. Button just needs a dragout event handler that works with IE.

[bill]

Looks like an IE7 problem with the :hover tag being used in the test file (for the custom style). Seems to work OK for the button labeled "big". I'll update the test file to use dijitButtonHover, or maybe redefine baseClass to be Acme so we get styles like .AcmeHover?

[bill]

(In [11889]) Make "hovering" CSS and "focused" CSS independent, so that we can use complementary effects for hover state and focus state. Also fix button CSS customization example. Fixes #4975, #5428.