The Base-IE of Windows Vista (EOL in 2017) is IE7 and the Base-IE of Windows 7 (EOL in 2020) is IE8. So IE7 and IE8 issues are not only in the EOL-OS WinXP.
I do not have access to any IE7 so I cannot test the contextmenu with that.
I have just push up a commit that adds support for IE8 into the contextmenu (git-master of contextmenu needs RC 1.1-git). I will backport the change into the version 2 release I'm planning for RC 1.0.
Phil