Bug: can't delete popup result when URLbar gets focus

[fang5566]

reproduce this bug on my computer(Firefox 17 aurora):

1. disable instanly preview every result of awesomebar popup on hover/up/down option.
2. keep an open tab and click the new tab button(a "+"like button) on its right to open a new tab.
3. the urlbar gets focus and shows "Go to a page" in its container.
4. click the dropdown arrow to show its results.
5. press delete key won't delete any of the results.

disable or uninstall the add on will fix this.