The phrase "tab button" refers to a key found on a computer keyboard or a digital device that you can press to move to the next option or field on a webpage or document. Full definition
So it could remove the home button in favor of a display - embedded fingerprint sensor and virtual home, back and open tabs buttons. (ibtimes.com)
Microsoft seems to have added a small button next to the open New tab button in Internet Explorer version 11.0.15063.0 on Windows 10 Creators Update v1703. (thewindowsclub.com)
YVES SAINT LAURENT by TOM FORD sport coat comes in dark taupe velvet and features a notch lapel, triple patch pockets, unique tab button cuffs, and top stitching throughout. (1stdibs.com)