Popup button enhancement

[danvim]

• initial button selection. RHS buttons initially select right button (Mimicking Google Keyboard)
• Increase area
• Timer/ TimerTask: Long press for duration to summon popupWindow, without ACTION_MOVE Runnanble, Handler, UIThread may be involved, or used instead of Timer.
• Fix the issue which pulling the navigation drawer also displays an overlay of a popupWindow of a key near the pulling point. Reference: http://stackoverflow.com/questions/18430186/how-do-i-close-the-keyboard-when-the-navigation-drawer-opens

[danvim]

Done in commit 74dbebd561338c921d6b35fdcb921aa34a61d9d1