Rated 4 out of 5 stars

Platform:
[18:54:47.972] "Mozilla/5.0 (Windows NT 6.1; WOW64; rv:13.0) Gecko/20100101 Firefox/13.0"

Build:
changeset - 92132:f16e48c88ac3
GECKO130_2012042512_RELBRANCH
FIREFOX_13_0b1_BUILD1
FIREFOX_13_0b1_RELEASE

Omnibar version:
0.7.11.20111111

Reproduce steps:
0. Open any site, about:newtab is just OK
1. Type anything in url bar
2. ALT + ENTER

Result:
Firefox is trying to understand/open what you typed in the CURRENT TAB however she should did this in a NEW TAB
This should be fixed by disabling Omnibar, so it's Omnibar's fault

This review is for a previous version of the add-on (0.7.11.20111111).  This user has a previous review of this add-on.

Posted a new update that should address this. Thanks for the report.