I know it doesn’t actually act on it, but when I test IE 9 in IE 7 browser mode in IE 7 standards mode it returns the box-sizing property. I’m not sure if this is because I’m emulating IE 7 or if the real IE 7 has this property to. Ultimately I’m trying to determine if I should be using the border-box box sizing in my calculations.
var usingBorderBox = ieVersion > 0.0 && ieVersion < 8.0
|| ((containerComputedStyle.boxSizing === 'border-box')
&& (contentComputedStyle.boxSizing === 'border-box'))
No, IE 7 does not support this property (it’s a CSS 3 property). This is just another reason why I use a virtual machine with IE 7 installed when I need to do browser testing. There’s an upsetting amount of legacy behavior that IE 9 doesn’t emulate when in IE 7 or 8 mode unfortunately.