Log Message:
Update to 1.8.1:

=== Release 1.8.1 ===
build: install graphics tabs/ for gtk-2.0 theme (bug #11839) bis
panel-plugin: fit button inside a single panel row
build: install graphics tabs/ for gtk-2.0 theme (bug #11839)

=== Release 1.8.0 ===
gtkrc: always show steppers
gtkrc: theme GtkNotebook
gtkrc: fix top tabs gap
gtkrc: set background tabs less opaque
gtkrc: no need for bg[ACTIVE], use shade on fg[ACTIVE], and redefine tabs
border
gtkrc: fix syntax and switch fg[NORMAL] to @notes_fg_color
build: remove soname versioning and install panel plugin to
$datadir/xfce4/panel/plugins
build: bump automake to 1.13
build: adjust to newer AM/AC macros
build: fix s/AM_CFLAGS/AM_CPPFLAGS
build: Uinstall hook for icon cache file