firefox have a "gap" between tabs and the panel

[Mzombira]

Binary package hint: firefox

When I have firefox open but in the minimized and I click on a link in gwibber, firefox pop-up but don't get the focus and there a strange gap between the tab and the panel of unity. I join a screenshot. If I minimize firefox and reopen it the gap is gone

ProblemType: Bug
DistroRelease: Ubuntu 11.04
Package: firefox 4.0+nobinonly-0ubuntu2
ProcVersionSignature: Ubuntu 2.6.38-8.42-generic 2.6.38.2
Uname: Linux 2.6.38-8-generic x86_64
NonfreeKernelModules: nvidia
Architecture: amd64
Date: Tue Apr 19 18:10:07 2011
FirefoxPackages:
 firefox 4.0+nobinonly-0ubuntu2
 flashplugin-installer 10.2.159.1ubuntu1
 adobe-flashplugin N/A
 icedtea-plugin 1.1~20110406-0ubuntu2
InstallationMedia: Ubuntu 11.04 "Natty Narwhal" - Alpha amd64 (20110325)
ProcEnviron:
 LANGUAGE=fr_CA:en
 LANG=fr_CA.UTF-8
 SHELL=/bin/bash
SourcePackage: firefox
UpgradeStatus: Upgraded to natty on 2011-04-02 (17 days ago)