Lost inspect state when trying inspect element from Network tab

[ghost]

Hi,
I'm facing with a small issue that i started Firebug at Network tab then click to Inspect icon to inspect HTML element.
But after click to the icon, firebug change active tab to Inspector then render HTML source with highlight, then state of the icon come to inactive. I must click to it again to use Inspector.

With default developer tool, the icon state won't be lost.