487 translated messages.

Transifex (https://explore.transifex.com/xfce/).

`base_directory` is initialized in `construct()`, which is called in
`realize()`, so if the plugin is never shown (case of a panel on a
disconnected monitor), it can be null.

An edge case: when the panel starts on a disconnected monitor, so it is
hidden at startup, and then moved manually to a connected monitor.

Fixes: 5da7e405

Also none of the other types in `panel` have the Xfce prefix.

It worked as is but it's misleading since PanelBaseWindow is derivable.
A clean refactoring would be to use G_DECLARE_DERIVABLE_TYPE by
replacing the public fields of the instance structure with accessors and
`priv` with `get_instance_private()`. But that will be for later, as for
PanelPluginExternal in a previous commit.

Fixes: c7f32ce8

486 translated messages, 1 untranslated message.

Transifex (https://explore.transifex.com/xfce/).

487 translated messages.

Transifex (https://explore.transifex.com/xfce/).

487 translated messages.

Transifex (https://explore.transifex.com/xfce/).

487 translated messages.

Transifex (https://explore.transifex.com/xfce/).

487 translated messages.

Transifex (https://explore.transifex.com/xfce/).

462 translated messages, 25 untranslated messages.

Transifex (https://explore.transifex.com/xfce/).

484 translated messages, 3 untranslated messages.

Transifex (https://explore.transifex.com/xfce/).

487 translated messages.

Transifex (https://explore.transifex.com/xfce/).

485 translated messages, 2 untranslated messages.

Transifex (https://explore.transifex.com/xfce/).

487 translated messages.

Transifex (https://explore.transifex.com/xfce/).

462 translated messages, 25 untranslated messages.

Transifex (https://explore.transifex.com/xfce/).

487 translated messages.

Transifex (https://explore.transifex.com/xfce/).

487 translated messages.

Transifex (https://explore.transifex.com/xfce/).

487 translated messages.

Transifex (https://explore.transifex.com/xfce/).

487 translated messages.

Transifex (https://explore.transifex.com/xfce/).

487 translated messages.

Transifex (https://explore.transifex.com/xfce/).

487 translated messages.

Transifex (https://explore.transifex.com/xfce/).

487 translated messages.

Transifex (https://explore.transifex.com/xfce/).

464 translated messages, 23 untranslated messages.

Transifex (https://explore.transifex.com/xfce/).

487 translated messages.

Transifex (https://explore.transifex.com/xfce/).

487 translated messages.

Transifex (https://explore.transifex.com/xfce/).

487 translated messages.

Transifex (https://explore.transifex.com/xfce/).

487 translated messages.

Transifex (https://explore.transifex.com/xfce/).

487 translated messages.

Transifex (https://explore.transifex.com/xfce/).

446 translated messages, 41 untranslated messages.

Transifex (https://explore.transifex.com/xfce/).

486 translated messages, 1 untranslated message.

Transifex (https://explore.transifex.com/xfce/).

434 translated messages, 53 untranslated messages.

Transifex (https://explore.transifex.com/xfce/).