Browsing English (United Kingdom) translation

This is a GTK+ button label for yes/no/always/never questions.
The '_' comes before the hotkey character.

This is an error message reported when a .zip file (or whatever) that
we need can't be located.

This prompt is shown to the user when they click the "Cancel" button,
to confirm they really want to stop. It's a yes/no question.

The opposite of "next", used as a UI button label.

This is a GTK+ button label. The '_' comes before the hotkey character.
"Back" might be using 'B' in English. This button brings up a file
dialog where the end-user can navigate to and select files.

All the "BUG:" strings are generally meant to be seen by developers,
not end users. They represent programming errors and configuration
file problems.
This is shown if the configuration file has specified two cd-roms (or
whatever) with the same media id, which is a bug the developer must
fix before shipping her installer.
"media id" refers to Setup.Media.id in the config file. It's not meant
to be a proper name, in this case.

This is shown if the configuration file has no installable options,
either because none are listed or they've all become disabled, which
is a bug the developer must fix before shipping her installer.

This is shown if the config file wants us to include the uninstaller
program with the rest of the files we write to disk, but didn't enable
the manifest support the installer needs. This is a bug the developer
must fix before shipping her installer.

This is shown if the config file wants us to install a manifest (a list
of everything we wrote to disk) but didn't enable Lua parser support
in the binary, which they need to handle Lua source code without
compiling it first (as it needs to be "parsed")...the manifest is
ultimately just an uncompiled Lua program that the installer generates.
This is a bug the developer must fix before shipping her installer.

This is shown if the config file wants us to add desktop menu items
but uninstaller support isn't enabled. It is considered bad taste
to add system menu items without a way to remove them. This is
a bug the developer must fix before shipping her installer.