So the question is about "tabs"?

Here is a hint

 [ddg://WWW::Mechanize::Firefox tab]
[ddg://WWW::Mechanize::Firefox active tab]
[ddg://WWW::Mechanize::Firefox switch tab]
[ddg://site:search.cpan.org WWW::Mechanize::Firefox switch tab]
[download]

Yields hints like

activate => 1,  # bring the tab to the foreground
autoclose => 0  # to prevent autoclosing of the Tab
->closeTab
tab => 'current',
->activateTab
->autoclose_tab
->tab
See also Firefox::Application for how to add more than one tab and how
+ to manipulate windows and tabs.
[download]

Thats as far as I looked because I don't use the module