关于popupwindow的问题们

stackoverflow果然是个好地方呀

http://stackoverflow.com/questions/3121232/android-popup-window-dismissal/3122696#3122696

This is because the popup window does not respond to onTouch or onKey events unless it has a background that != null.Check out some code I wrote to help with this. In the basic case you can to callPopupWindow#setBackgroundDrawable(new BitmapDrawable()) to force it to act the way you expect. You won't need your own onKey listener. You might also need to callPopupWindow#setOutsideTouchable(true) if you want it to go away when the user clicks outside of the window boundaries.

Extended esoteric answer:

The reason the background cannot be null is because of what happens in PopupWindow#preparePopup. If it detectsbackground != null it creates an instance of PopupViewContainer and callssetBackgroundDrawable on that and puts your content view in it. PopupViewContainer is basically a FrameLayout that listens for touch events and theKeyEvent.KEYCODE_BACK event to dismiss the window. If background == null, it doesn't do any of that and just uses your content view. You can, as an alternative to depending onPopupWindow to handle that, extend your root ViewGroup to behave the way you want.