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 very interested in how this is done? I think it's something to with PopupWindow.

Any ideas? Thanks in Advance.

What is the floating button on my phone?

A floating action button (FAB) is a circular button that triggers the primary action in your app's UI. This page shows you how to add the FAB to your layout, customize some of its appearance, and respond to button taps.

How do I get rid of floating buttons?

Go to Settings->Accessibility->Text and display->Color correction, and turn off "Color correction shortcut". This will remove the floating icon.

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.