Merge pull request #45 from MrArtichaut/master

Use CGRectIntegral to avoid blurred content by MrArtichaut
Update WYPopoverController.m

Fix issue #47
window may has a background subview while it's hidden, that cause the popover can not be shown up.
Merge pull request #48 from hijackwang/patch-1

Select first "rootView" which is not hidden by hijackwang
Merge pull request #1 from nicolaschengdev/master

Merge from originam