You can also use a command in mIRC:
/url [on | off | show | hide | -dran] [[N | mark ] | address]
Show or hides the Url list window, and allows you to modify the current list of addresses in it.
The -r switch deletes the Nth item, or all items that match the mark you specify.
The -an switches allow you to open a browser window to an address, where -a = activate browser, and -n = use a new browser window.