Add the widget library to the wesnoth-lib domain and update the helper files.

data/gui/default.cfg

@@ -1,3 +1,4 @@
+#textdomain wesnoth-lib
 ###
 ### Defines a gui, all widgets and windows used in a certain 'theme'.
 ###

po/wesnoth-lib/FINDCFG

@@ -1 +1,2 @@
 echo 'data/core/terrain.cfg'
+find data/gui/ -name '*.cfg' -print

po/wesnoth-lib/POTFILES.in

@@ -12,8 +12,10 @@ src/gui/widgets/event_handler.cpp
 src/gui/widgets/grid.cpp
 src/gui/widgets/helper.cpp
 src/gui/widgets/label.cpp
+src/gui/widgets/panel.cpp
 src/gui/widgets/settings.cpp
 src/gui/widgets/text_box.cpp
+src/gui/widgets/text.cpp
 src/gui/widgets/tooltip.cpp
 src/gui/widgets/widget.cpp
 src/gui/widgets/window_builder.cpp

po/wesnoth/FINDCFG

@@ -1,2 +1,2 @@
-find data -name themes -prune -o -name editor-groups.cfg -prune -o -name '*.cfg' -print
+find data -name themes -prune -o -name editor-groups.cfg -prune -o -name gui -prune -o -name '*.cfg' -print
 find data/themes/ -name editor.cfg -prune -o -name '*.cfg' -print