Android : Floating Clickable Icon over Screen?

There's an Android Application called Smart Taskbar that manages to Pin a small SemiTransparent Icon over the screen...The icon remains visible over ALL the activites (including the home screen). The Icon is Clickable (/Touchable), and it does popopen a Small Popup window which the user can interact with.

I'm ve开发者_Python百科ry interested in how this is done? I think it's something to with PopupWindow.

Any ideas? Thanks in Advance.

I recently experimented with this.

See this question: Creating a system overlay window (always on top) - the solution is virtually the same, but you need to set TYPE_SYSTEM_ALERT in the layout params instead of TYPE_SYSTEM_OVERLAY.