gaupol/dialogs/preferences.py

Source code for module gaupol.dialogs.preferences from file gaupol/dialogs/preferences.py.

  1
  2
  3
  4
  5
  6
  7
  8
  9
 10
 11
 12
 13
 14
 15
 16
 17
 18
 19
 20
 21
 22
 23
 24
 25
 26
 27
 28
 29
 30
 31
 32
 33
 34
 35
 36
 37
 38
 39
 40
 41
 42
 43
 44
 45
 46
 47
 48
 49
 50
 51
 52
 53
 54
 55
 56
 57
 58
 59
 60
 61
 62
 63
 64
 65
 66
 67
 68
 69
 70
 71
 72
 73
 74
 75
 76
 77
 78
 79
 80
 81
 82
 83
 84
 85
 86
 87
 88
 89
 90
 91
 92
 93
 94
 95
 96
 97
 98
 99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
251
252
253
254
255
256
257
258
259
260
261
262
263
264
265
266
267
268
269
270
271
272
273
274
275
276
277
278
279
280
281
282
283
284
285
286
287
288
289
290
291
292
293
294
295
296
297
298
299
300
301
302
303
304
305
306
307
308
309
310
311
312
313
314
315
316
317
318
319
320
321
322
323
324
325
326
327
328
329
330
331
332
333
334
335
336
337
338
339
340
341
342
343
344
345
346
347
348
349
350
351
352
353
354
355
356
357
358
359
360
361
362
363
364
365
366
367
368
369
370
371
372
373
374
375
376
377
378
379
380
381
382
383
384
385
386
387
388
389
390
391
392
393
394
395
396
397
398
399
400
401
402
403
404
405
406
407
408
409
410
411
412
413
414
415
416
417
418
419
420
421
422
423
424
425
426
427
428
429
430
431
432
433
434
435
436
437
438
439
440
441
442
443
444
445
446
447
448
449
450
451
452
453
454
455
456
457
458
459
460
461
462
463
464
465
466
467
468
469
470
471
472
473
474
475
476
477
478
479
480
481
482
483
484
485
486
487
488
489
490
491
492
493
494
495
496
497
498
499
500
501
502
503
504
505
506
507
508
509
510
511
512
513
514
515
516
517
518
519
520
521
522
523
524
525
526
527
528
529
530
531
532
533
534
535
536
537
538
539
540
541
542
543
544
545
546
547
548
549
550
551
552
553
554
555
556
557
558
559
560
561
562
563
564
565
566
567
568
569
570
571
572
573
574
575
576
577
578
579
580
581
582
583
584
585
586
587
588
589
590
591
592
593
594
595
596
597
598
599
# -*- coding: utf-8 -*-

# Copyright (C) 2005 Osmo Salomaa
#
# 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 3 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, see <http://www.gnu.org/licenses/>.

"""Dialog for editing preferences."""

import aeidon
import gaupol
_ = aeidon.i18n._

from gi.repository import Gtk
from gi.repository import Pango

__all__ = ("PreferencesDialog",)


class EditorPage(aeidon.Delegate, gaupol.BuilderDialog):

    """Editor preferences page."""

    _widgets = ("editor_default_font_check",
                "editor_font_button",
                "editor_font_hbox",
                "editor_length_cell_check",
                "editor_length_combo",
                "editor_length_edit_check",
                "editor_length_hbox",
                "editor_spell_check_check")

    def __init__(self, master, application):
        """Initialize an :class:`EditorPage` instance."""
        aeidon.Delegate.__init__(self, master)
        self._set_attributes(self._widgets, "editor_")
        self.application = application
        self._init_length_combo()
        self._init_values()

    def _get_custom_font(self):
        """Return custom font as string."""
        context = Gtk.Label().get_pango_context()
        font_desc = context.get_font_description()
        font = gaupol.conf.editor.custom_font
        custom_font_desc = Pango.FontDescription(font)
        font_desc.merge(custom_font_desc, True)
        return font_desc.to_string()

    def _init_length_combo(self):
        """Initialize the line length combo box."""
        store = Gtk.ListStore(str)
        for label in (x.label for x in gaupol.length_units):
            store.append((label,))
        self._length_combo.set_model(store)
        renderer = Gtk.CellRendererText()
        self._length_combo.pack_start(renderer, expand=True)
        self._length_combo.add_attribute(renderer, "text", 0)

    def _init_values(self):
        """Initialize default values for widgets."""
        use_custom = gaupol.conf.editor.use_custom_font
        self._default_font_check.set_active(not use_custom)
        self._font_hbox.set_sensitive(use_custom)
        self._font_button.set_font_name(self._get_custom_font())
        show_cell = gaupol.conf.editor.show_lengths_cell
        show_edit = gaupol.conf.editor.show_lengths_edit
        self._length_hbox.set_sensitive(show_cell or show_edit)
        self._length_cell_check.set_active(show_cell)
        self._length_edit_check.set_active(show_edit)
        self._length_combo.set_active(gaupol.conf.editor.length_unit)
        if gaupol.util.gtkspell_available():
            inline = gaupol.conf.spell_check.inline
            self._spell_check_check.set_active(inline)
            self._spell_check_check.set_sensitive(True)
        else: # GtkSpell not available
            self._spell_check_check.set_active(False)
            self._spell_check_check.set_sensitive(False)

    def _on_default_font_check_toggled(self, check_button):
        """Save default font usage."""
        use_custom = not check_button.get_active()
        gaupol.conf.editor.use_custom_font = use_custom
        self._font_hbox.set_sensitive(use_custom)

    def _on_font_button_font_set(self, font_button):
        """Save custom font."""
        gaupol.conf.editor.custom_font = font_button.get_font_name()

    def _on_length_cell_check_toggled(self, check_button):
        """Save line length display on cells."""
        gaupol.conf.editor.show_lengths_cell = check_button.get_active()
        show_cell = gaupol.conf.editor.show_lengths_cell
        show_edit = gaupol.conf.editor.show_lengths_edit
        self._length_hbox.set_sensitive(show_cell or show_edit)

    def _on_length_combo_changed(self, combo_box):
        """Save line length unit."""
        index = combo_box.get_active()
        gaupol.conf.editor.length_unit = gaupol.length_units[index]

    def _on_length_edit_check_toggled(self, check_button):
        """Save line length display on text views."""
        gaupol.conf.editor.show_lengths_edit = check_button.get_active()
        show_cell = gaupol.conf.editor.show_lengths_cell
        show_edit = gaupol.conf.editor.show_lengths_edit
        self._length_hbox.set_sensitive(show_cell or show_edit)

    def _on_spell_check_check_toggled(self, check_button):
        """Save inline spell-check use on text views."""
        gaupol.conf.spell_check.inline = check_button.get_active()


class ExtensionPage(aeidon.Delegate, gaupol.BuilderDialog):

    """Extension activation and preferences page."""

    _widgets = ("extensions_about_button",
                "extensions_help_button",
                "extensions_link_button",
                "extensions_preferences_button",
                "extensions_toolbar",
                "extensions_tree_view")

    def __init__(self, master, application):
        """Initialize an :class:`ExtensionPage` instance."""
        aeidon.Delegate.__init__(self, master)
        self._set_attributes(self._widgets, "extensions_")
        self.application = application
        self.manager = self.application.extension_manager
        self._init_tree_view()
        self._init_toolbar()
        self._init_values()
        self._init_sensitivities()

    def _get_selected_module(self):
        """Return the selected module in the tree view or ``None``."""
        selection = self._tree_view.get_selection()
        store, itr = selection.get_selected()
        if itr is None: return None
        return store.get_value(itr, 0)

    def _init_sensitivities(self):
        """Initialize button sensitivities."""
        self._about_button.set_sensitive(False)
        self._help_button.set_sensitive(False)
        self._preferences_button.set_sensitive(False)

    def _init_toolbar(self):
        """Initialize the tree view inline toolbar."""
        self._toolbar.set_icon_size(Gtk.IconSize.MENU)
        style = self._toolbar.get_style_context()
        style.add_class(Gtk.STYLE_CLASS_INLINE_TOOLBAR)

    def _init_tree_view(self):
        """Initialize the tree view."""
        store = Gtk.ListStore(str, bool, str)
        self._tree_view.set_model(store)
        selection = self._tree_view.get_selection()
        selection.set_mode(Gtk.SelectionMode.SINGLE)
        selection.connect("changed", self._on_tree_view_selection_changed)
        renderer = Gtk.CellRendererToggle()
        renderer.props.activatable = True
        renderer.props.xpad = 6
        renderer.connect("toggled", self._on_tree_view_cell_toggled)
        column = Gtk.TreeViewColumn("", renderer, active=1)
        self._tree_view.append_column(column)
        renderer = Gtk.CellRendererText()
        renderer.props.ellipsize = Pango.EllipsizeMode.END
        column = Gtk.TreeViewColumn("", renderer, markup=2)
        self._tree_view.append_column(column)

    def _init_values(self):
        """Initialize default values for widgets."""
        self._link_button.set_uri(gaupol.EXTENSIONS_URL)
        store = self._tree_view.get_model()
        extensions = []
        for module in self.manager.get_modules():
            metadata = self.manager.get_metadata(module)
            if metadata.get_field_boolean("Hidden", False): continue
            markup = "<b>{}</b>\n{}".format(
                metadata.get_name(), metadata.get_description())
            extensions.append((module, markup))
        extensions.sort(key=lambda x: x[1])
        for module, markup in extensions:
            active = module in gaupol.conf.extensions.active
            store.append((module, active, markup))

    def _on_about_button_clicked(self, *args):
        """Construct and show a :class:`Gtk.AboutDialog` for extension."""
        module = self._get_selected_module()
        metadata = self.manager.get_metadata(module)
        dialog = Gtk.AboutDialog()
        dialog.set_transient_for(self._dialog)
        dialog.set_program_name(metadata.get_name())
        dialog.set_comments(metadata.get_description())
        dialog.set_logo_icon_name("gaupol")
        if metadata.has_field("Version"):
            dialog.set_version(metadata.get_field("Version"))
        if metadata.has_field("Copyright"):
            copyright = "\n".join(metadata.get_field_list("Copyright"))
            dialog.set_copyright(copyright)
        if metadata.has_field("Website"):
            dialog.set_website(metadata.get_field("Website"))
            label = _("{} Extension Website").format(metadata.get_name())
            dialog.set_website_label(label)
        if metadata.has_field("Authors"):
            dialog.set_authors(metadata.get_field_list("Authors"))
        gaupol.util.flash_dialog(dialog)

    def _on_help_button_clicked(self, *args):
        """Show extension's own documentation."""
        module = self._get_selected_module()
        self.manager.show_help(module)

    def _on_preferences_button_clicked(self, *args):
        """Show extension's preferences dialog."""
        module = self._get_selected_module()
        self.manager.show_preferences_dialog(module, self._dialog)

    def _on_tree_view_cell_toggled(self, renderer, path):
        """Activate or deactivate toggled extension."""
        store = self._tree_view.get_model()
        module = store[path][0]
        active = store[path][1]
        if active:
            try:
                self.manager.teardown_extension(module)
                gaupol.conf.extensions.active.remove(module)
            except gaupol.DependencyError:
                title = _("Cannot deactivate extension")
                message = _('Extension "{}" is required by other extensions.')
                message = message.format(store[path][2])
                dialog = gaupol.ErrorDialog(self._dialog, title, message)
                dialog.add_button(_("_OK"), Gtk.ResponseType.OK)
                dialog.set_default_response(Gtk.ResponseType.OK)
                gaupol.util.flash_dialog(dialog)
        else: # Activating extension.
            self.manager.setup_extension(module)
            gaupol.conf.extensions.active.append(module)
        for row in store:
            row[1] = self.manager.is_active(row[0])
        selection = self._tree_view.get_selection()
        selection.emit("changed")

    def _on_tree_view_selection_changed(self, *args):
        """Set sensitivities of buttons."""
        module = self._get_selected_module()
        have_selection = self._get_selected_module() is not None
        self._about_button.set_sensitive(have_selection)
        if module in gaupol.conf.extensions.active:
            has_help = self.manager.has_help(module)
            self._help_button.set_sensitive(has_help)
            has_preferences = self.manager.has_preferences_dialog(module)
            self._preferences_button.set_sensitive(has_preferences)
        else: # Cannot query unimported extensions.
            self._help_button.set_sensitive(False)
            self._preferences_button.set_sensitive(False)


class FilePage(aeidon.Delegate, gaupol.BuilderDialog):

    """File preferences page."""

    _widgets = ("file_add_button",
                "file_auto_check",
                "file_down_button",
                "file_tree_view",
                "file_locale_check",
                "file_remove_button",
                "file_toolbar",
                "file_up_button")

    def __init__(self, master, application):
        """Initialize a :class:`FilePage` instance."""
        aeidon.Delegate.__init__(self, master)
        self._set_attributes(self._widgets, "file_")
        self.application = application
        self._init_tree_view()
        self._init_toolbar()
        self._init_values()

    def _get_selected_row(self):
        """Return the selected row in the tree view or ``None``."""
        selection = self._tree_view.get_selection()
        store, itr = selection.get_selected()
        if itr is None: return None
        path = store.get_path(itr)
        return gaupol.util.tree_path_to_row(path)

    def _init_toolbar(self):
        """Initialize the tree view inline toolbar."""
        self._toolbar.set_icon_size(Gtk.IconSize.MENU)
        style = self._toolbar.get_style_context()
        style.add_class(Gtk.STYLE_CLASS_INLINE_TOOLBAR)
        theme = Gtk.IconTheme.get_default()
        # Tool buttons in the UI file are specified as symbolic icons
        # by name, found in adwaita-icon-theme, if missing in another
        # theme fall back to non-symbolic icons.
        if not all((theme.has_icon(self._add_button.get_icon_name()),
                    theme.has_icon(self._remove_button.get_icon_name()),
                    theme.has_icon(self._up_button.get_icon_name()),
                    theme.has_icon(self._down_button.get_icon_name()))):

            self._add_button.set_icon_name("list-add")
            self._remove_button.set_icon_name("list-remove")
            self._up_button.set_icon_name("go-up")
            self._down_button.set_icon_name("go-down")

    def _init_tree_view(self):
        """Initialize the fallback encoding tree view."""
        selection = self._tree_view.get_selection()
        selection.set_mode(Gtk.SelectionMode.SINGLE)
        update = lambda x, self: self._set_sensitivities()
        selection.connect("changed", update, self)
        store = Gtk.ListStore(str)
        self._tree_view.set_model(store)
        renderer = Gtk.CellRendererText()
        column = Gtk.TreeViewColumn("", renderer, text=0)
        self._tree_view.append_column(column)

    def _init_values(self):
        """Initialize default values for widgets."""
        self._auto_check.set_active(gaupol.conf.encoding.try_auto)
        self._auto_check.set_sensitive(aeidon.util.chardet_available())
        self._locale_check.set_active(gaupol.conf.encoding.try_locale)
        self._reload_tree_view()

    def _on_add_button_clicked(self, *args):
        """Add a new fallback encoding."""
        dialog = gaupol.EncodingDialog(self._dialog)
        response = gaupol.util.run_dialog(dialog)
        encoding = dialog.get_encoding()
        dialog.destroy()
        if response != Gtk.ResponseType.OK: return
        if encoding is None: return
        if encoding in gaupol.conf.encoding.fallback: return
        gaupol.conf.encoding.fallback.append(encoding)
        self._reload_tree_view()
        self._tree_view.grab_focus()
        store = self._tree_view.get_model()
        self._tree_view.set_cursor(len(store) - 1)

    def _on_auto_check_toggled(self, check_button):
        """Save encoding auto-detection usage."""
        gaupol.conf.encoding.try_auto = check_button.get_active()

    def _on_down_button_clicked(self, *args):
        """Move the selected fallback encoding down."""
        row = self._get_selected_row()
        encodings = gaupol.conf.encoding.fallback
        encodings.insert(row+1, encodings.pop(row))
        self._reload_tree_view()
        self._tree_view.grab_focus()
        self._tree_view.set_cursor(row+1)

    def _on_locale_check_toggled(self, check_button):
        """Save locale encoding usage."""
        gaupol.conf.encoding.try_locale = check_button.get_active()

    def _on_remove_button_clicked(self, *args):
        """Remove the selected fallback encoding."""
        row = self._get_selected_row()
        gaupol.conf.encoding.fallback.pop(row)
        self._reload_tree_view()
        self._tree_view.grab_focus()
        store = self._tree_view.get_model()
        if len(store) <= 0: return
        self._tree_view.set_cursor(max(row-1, 0))

    def _on_up_button_clicked(self, *args):
        """Move the selected fallback encoding up."""
        row = self._get_selected_row()
        encodings = gaupol.conf.encoding.fallback
        encodings.insert(row-1, encodings.pop(row))
        self._reload_tree_view()
        self._tree_view.grab_focus()
        self._tree_view.set_cursor(row-1)

    def _reload_tree_view(self):
        """Reload the fallback encoding tree view."""
        store = self._tree_view.get_model()
        store.clear()
        for encoding in gaupol.conf.encoding.fallback:
            store.append((aeidon.encodings.code_to_long_name(encoding),))
        self._set_sensitivities()

    def _set_sensitivities(self):
        """Set the fallback tree view button sensitivities."""
        store = self._tree_view.get_model()
        row = self._get_selected_row()
        row = (-1 if row is None else row)
        self._remove_button.set_sensitive(row >= 0)
        self._up_button.set_sensitive(row > 0)
        self._down_button.set_sensitive(0 <= row < len(store) - 1)


class PreviewPage(aeidon.Delegate, gaupol.BuilderDialog):

    """Preview preferences page."""

    _widgets = ("preview_app_combo",
                "preview_command_entry",
                "preview_force_utf_8_check",
                "preview_offset_spin")

    def __init__(self, master, application):
        """Initialize a :class:`PreviewPage` instance."""
        aeidon.Delegate.__init__(self, master)
        self._set_attributes(self._widgets, "preview_")
        self.application = application
        self._init_app_combo()
        self._init_values()

    def _init_app_combo(self):
        """Initialize the application combo box."""
        store = Gtk.ListStore(str)
        self._app_combo.set_model(store)
        for label in (x.label for x in aeidon.players):
            store.append((label,))
        store.append((gaupol.COMBO_SEPARATOR,))
        store.append((_("Custom"),))
        renderer = Gtk.CellRendererText()
        self._app_combo.pack_start(renderer, expand=True)
        self._app_combo.add_attribute(renderer, "text", 0)
        func = gaupol.util.separate_combo
        self._app_combo.set_row_separator_func(func, None)

    def _init_values(self):
        """Initialize default values for widgets."""
        store = self._app_combo.get_model()
        self._app_combo.set_active((len(store) - 1 if
                                    gaupol.conf.preview.use_custom_command else
                                    gaupol.conf.preview.player))

        self._command_entry.set_text(gaupol.util.get_preview_command())
        editable = gaupol.conf.preview.use_custom_command
        self._command_entry.set_editable(editable)
        self._force_utf_8_check.set_active(gaupol.conf.preview.force_utf_8)
        self._offset_spin.set_value(gaupol.conf.preview.offset)

    def _on_app_combo_changed(self, combo_box):
        """Save video player and show it's command."""
        index = combo_box.get_active()
        use_custom = not index in aeidon.players
        gaupol.conf.preview.use_custom_command = use_custom
        if not use_custom:
            gaupol.conf.preview.player = aeidon.players[index]
        self._command_entry.set_text(gaupol.util.get_preview_command())
        editable = gaupol.conf.preview.use_custom_command
        self._command_entry.set_editable(editable)

    def _on_command_entry_changed(self, entry):
        """Save custom command."""
        if not gaupol.conf.preview.use_custom_command: return
        gaupol.conf.preview.custom_command = entry.get_text()

    def _on_force_utf_8_check_toggled(self, check_button):
        """Save forced UTF-8 preview setting."""
        gaupol.conf.preview.force_utf_8 = check_button.get_active()
        self._command_entry.set_text(gaupol.util.get_preview_command())

    def _on_offset_spin_value_changed(self, spin_button):
        """Save start position offset."""
        gaupol.conf.preview.offset = spin_button.get_value()


class VideoPage(aeidon.Delegate, gaupol.BuilderDialog):

    """Video preferences page."""

    _widgets = ("video_subtitle_bg_check",
                "video_subtitle_color_button",
                "video_subtitle_font_button",
                "video_time_bg_check",
                "video_time_color_button",
                "video_time_font_button")

    def __init__(self, master, application):
        """Initialize a :class:`PreviewPage` instance."""
        aeidon.Delegate.__init__(self, master)
        self._set_attributes(self._widgets, "video_")
        self.application = application
        self.conf = gaupol.conf.video_player
        self._init_subtitle_values()
        self._init_time_values()

    def _get_custom_font(self, font):
        """Return custom font as string."""
        context = Gtk.Label().get_pango_context()
        font_desc = context.get_font_description()
        custom_font_desc = Pango.FontDescription(font)
        font_desc.merge(custom_font_desc, True)
        return font_desc.to_string()

    def _init_subtitle_values(self):
        """Initialize default values for subtitle widgets."""
        self._subtitle_bg_check.set_active(self.conf.subtitle_background)
        color = gaupol.util.hex_to_rgba(self.conf.subtitle_color)
        color.alpha = self.conf.subtitle_alpha
        self._subtitle_color_button.set_rgba(color)
        font = self._get_custom_font(self.conf.subtitle_font)
        self._subtitle_font_button.set_font_name(font)

    def _init_time_values(self):
        """Initialize default values for time widgets."""
        self._time_bg_check.set_active(self.conf.time_background)
        color = gaupol.util.hex_to_rgba(self.conf.time_color)
        color.alpha = self.conf.time_alpha
        self._time_color_button.set_rgba(color)
        font = self._get_custom_font(self.conf.time_font)
        self._time_font_button.set_font_name(font)

    def _on_subtitle_bg_check_toggled(self, check_button):
        """Save subtitle background use."""
        self.conf.subtitle_background = check_button.get_active()

    def _on_subtitle_color_button_color_set(self, color_button):
        """Save subtitle color."""
        color = color_button.get_rgba()
        self.conf.subtitle_color = gaupol.util.rgba_to_hex(color)
        self.conf.subtitle_alpha = color.alpha

    def _on_subtitle_font_button_font_set(self, font_button):
        """Save subtitle font."""
        self.conf.subtitle_font = font_button.get_font_name()

    def _on_time_bg_check_toggled(self, check_button):
        """Save time background use."""
        self.conf.time_background = check_button.get_active()

    def _on_time_color_button_color_set(self, color_button):
        """Save time color."""
        color = color_button.get_rgba()
        self.conf.time_color = gaupol.util.rgba_to_hex(color)
        self.conf.time_alpha = color.alpha

    def _on_time_font_button_font_set(self, font_button):
        """Save time font."""
        self.conf.time_font = font_button.get_font_name()


class PreferencesDialog(gaupol.BuilderDialog):

    """Dialog for editing preferences."""

    _widgets = ("notebook",)

    def __init__(self, parent, application):
        """Initialize a :class:`PreferencesDialog` instance."""
        gaupol.BuilderDialog.__init__(self,
                                      "preferences-dialog.ui",
                                      connect_signals=False)

        self._editor_page = EditorPage(self, application)
        self._extension_page = ExtensionPage(self, application)
        self._file_page = FilePage(self, application)
        self._preview_page = PreviewPage(self, application)
        self._video_page = VideoPage(self, application)
        self._builder.connect_signals(self._get_callbacks())
        self.connect("response", self._on_response)
        aeidon.util.connect(self, "_notebook", "switch-page")
        self.set_transient_for(parent)
        self.set_default_response(Gtk.ResponseType.CLOSE)
        self.set_response_sensitive(Gtk.ResponseType.HELP, False)

    def _get_callbacks(self):
        """Return a dictionary mapping names to callback methods."""
        callbacks = {}
        for page in (self._editor_page,
                     self._extension_page,
                     self._file_page,
                     self._preview_page,
                     self._video_page):

            for name in (x for x in dir(page) if x.startswith("_on_")):
                callbacks[name] = getattr(page, name)
        return callbacks

    def _on_notebook_switch_page(self, notebook, page, index):
        """Set sensitivity of the help button."""
        # Use help on the preview page, which is the fourth.
        self.set_response_sensitive(Gtk.ResponseType.HELP, index == 3)

    def _on_response(self, dialog, response):
        """Do not send response if browsing help."""
        if response == Gtk.ResponseType.HELP:
            gaupol.util.show_uri(gaupol.PREVIEW_HELP_URL)
            self.stop_emission("response")