Add new PaletteMenuItem widget for usage in mixed content Palettes

As Palettes can either include a Gtk.Menu or a Gtk.Window we
have to use a "false" menu when we want to have both
functionality in a Palette. This is a new class PaletteMenuItem
for those use cases.

Code highly based on the work from Gonzalo Odiard. The API is
based on the one from GtkImageMenuItem [1].

[1] http://developer.gnome.org/gtk3/3.4/GtkImageMenuItem.html

Signed-off-by: Simon Schampijer <simon@laptop.org>
Acked-by: Manuel Quiñones <manuq@laptop.org>

src/sugar3/graphics/Makefile.am

@@ -12,6 +12,7 @@ sugar_PYTHON =              \
 	objectchooser.py        \
 	palettegroup.py         \
 	palette.py              \
+	palettemenuitem.py	\
 	palettewindow.py        \
 	panel.py                \
 	radiopalette.py         \

src/sugar3/graphics/palettemenuitem.py

@@ -0,0 +1,121 @@
+# Copyright 2012 One Laptop Per Child
+#
+# This program is free software; you can redistribute it and/or modify
+# it under the terms of the GNU General Public License as published by
+# the Free Software Foundation; either version 2 of the License, or
+# (at your option) any later version.
+#
+# This program is distributed in the hope that it will be useful,
+# but WITHOUT ANY WARRANTY; without even the implied warranty of
+# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+# GNU General Public License for more details.
+#
+# You should have received a copy of the GNU General Public License
+# along with this program; if not, write to the Free Software
+# Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA  02110-1301  USA
+
+import logging
+
+from gi.repository import GObject
+from gi.repository import Gtk
+
+from sugar3.graphics.icon import Icon
+from sugar3.graphics import style
+
+
+class PaletteMenuItemSeparator(Gtk.HSeparator):
+    """A HSeparator that can be styled in the theme"""
+
+    __gtype_name__ = 'SugarPaletteMenuItemSeparator'
+
+    def __init__(self):
+        Gtk.HSeparator.__init__(self)
+
+
+class PaletteMenuItem(Gtk.EventBox):
+
+    __gtype_name__ = 'SugarPaletteMenuItem'
+
+    __gsignals__ = {
+        'activate': (GObject.SignalFlags.RUN_FIRST, None, [])
+    }
+
+    def __init__(self, text_label=None, icon_name=None, text_maxlen=60,
+                 xo_color=None, file_name=None):
+        Gtk.EventBox.__init__(self)
+        self._sensitive = True
+        self.set_above_child(True)
+        self.icon = None
+
+        vbox = Gtk.VBox()
+        vbox.set_border_width(style.DEFAULT_PADDING)
+        self._hbox = Gtk.HBox()
+        if icon_name is not None:
+            self.icon = Icon(icon_name=icon_name,
+                        icon_size=Gtk.IconSize.SMALL_TOOLBAR)
+            if xo_color is not None:
+                self.icon.props.xo_color = xo_color
+            self._hbox.pack_start(self.icon, expand=False, fill=False,
+                                  padding=style.DEFAULT_PADDING)
+        elif file_name is not None:
+            self.icon = Icon(file=file_name,
+                             icon_size=Gtk.IconSize.SMALL_TOOLBAR)
+            if xo_color is not None:
+                self.icon.props.xo_color = xo_color
+            self._hbox.pack_start(self.icon, expand=False, fill=False,
+                                  padding=style.DEFAULT_PADDING)
+
+        align = Gtk.Alignment(xalign=0.0, yalign=0.5, xscale=0.0, yscale=0.0)
+        self.label = Gtk.Label(text_label)
+        align.add(self.label)
+        self._hbox.pack_start(align, expand=True, fill=True,
+                        padding=style.DEFAULT_PADDING)
+        vbox.pack_start(self._hbox, expand=False, fill=False,
+                        padding=style.DEFAULT_PADDING)
+        self.add(vbox)
+
+        self.id_bt_release_cb = self.connect('button-release-event',
+                self.__button_release_cb)
+        self.id_enter_notify_cb = self.connect('enter-notify-event',
+                                               self.__enter_notify_cb)
+        self.id_leave_notify_cb = self.connect('leave-notify-event',
+                                               self.__leave_notify_cb)
+
+        self.show_all()
+
+    def __button_release_cb(self, widget, event):
+        self.emit('activate')
+
+    def __enter_notify_cb(self, widget, event):
+        self.modify_bg(Gtk.StateType.NORMAL,
+                       style.COLOR_BUTTON_GREY.get_gdk_color())
+
+    def __leave_notify_cb(self, widget, event):
+        self.modify_bg(Gtk.StateType.NORMAL,
+                       style.COLOR_BLACK.get_gdk_color())
+
+    def set_label(self, text_label):
+        text = '<span foreground="%s">' % style.COLOR_WHITE.get_html() + \
+                    text_label + '</span>'
+        self.label.set_markup(text)
+
+    def set_image(self, icon):
+        self._hbox.pack_start(icon, expand=False, fill=False,
+                              padding=style.DEFAULT_PADDING)
+        self._hbox.reorder_child(icon, 0)
+
+    def set_sensitive(self, sensitive):
+        if self._sensitive == sensitive:
+            return
+
+        self._sensitive = sensitive
+        if sensitive:
+            self.handler_unblock(self.id_bt_release_cb)
+            self.handler_unblock(self.id_enter_notify_cb)
+            self.handler_unblock(self.id_leave_notify_cb)
+        else:
+            self.handler_block(self.id_bt_release_cb)
+            self.handler_block(self.id_enter_notify_cb)
+            self.handler_block(self.id_leave_notify_cb)
+            self.modify_bg(Gtk.StateType.NORMAL,
+                           style.COLOR_BLACK.get_gdk_color())