Add drawer 'isOpen' class

[arcaballero]

There needs to be classes or methods after opening and closing the drawer

[Alexander Huang]

Does 'slide-end' event meet the needs ?

[arcaballero]

'slide-end' doesn't determine whether the drawer is open or closed right?
Would be great if you can target the drawer state with css, 'open' or 'closed'

[Alexander Huang]

slide-end event emit visible state of the drawer

[Alexander Huang]

Adding the class may increase the risk of style conflict, so that's my opinion.Thanks for your understanding.