In the top left corner of your screen you may see status icons, depending on what options you have toggled on/off. These are passive indicators, so clicking on them directly will have no effect.
They are as follows:
A web browser has user focus:
Click on a web browser to focus on it, and click off it or press ESC to exit and remove focus. Whilst a web browser has focus, it will prevent you from doing other things like moving your avatar.
The 3D Ruler is active:
To toggle this, hit B, or select/deselect it on the menu wheel (hit TAB).
The Laser is active:
To toggle this, hit L, or select/deselect it on the menu wheel (hit TAB).
Camera movement is locked:
To toggle this, hit 2.
Cursor is hidden:
To toggle this, hit 3.
3rd person camera has free Y axis movement:
To toggle this, hit 4.
FlyCam is active:
To toggle this, hit F, or select/deselect it on the menu wheel (hit TAB).
Webcam is active
To toggle this, select/deselect it on the menu wheel (hit TAB).
VOIP is active:
To toggle this, select/deselect it on the menu wheel (hit TAB).