QuickSettings

This small app can

- Adjust screen brightness,

- Turn sound on/off,

- Open Settings

- Turn Bluetooth on/off,

- Turn GPS on/off (on earlier Android versions),

- Turn flash light on/off.

- Open Developer settings.

It's not a widget, but looks like one, it's started with an icon and closes when clicking outside the app, as it is hovering on top of the home screen.

The light has 6 levels including automatic.

The picture does not quite represent the app, as it is more transparent.