Preferences: Remove deprecated GTK features (#1154)

* gpodderpreferences.ui: Save with Glade 3.38.2

* gpodderpreferences.ui: Add tab label children

* gpodderpreferences.ui: Return notebook pages to correct order

* gpodderpreferences.ui: Use named icons, replace stock-ids

* gpodderpreferences.ui: Remove extra rows and columns from table_video

* gpodderpreferences.ui: Use traditional indicator for CheckButtons

* gpodderpreferences.ui: Set can-focus to True where appropriate

* gpodderpreferences.ui: Add border-width to mygpo_config

* gpodderpreferences.ui: Add margins around dialog ButtonBox

* gpodderpreferences.ui: Replace gtk-close stock label with text

* preferences.py: Set transient for parent

* podcastdirectory.py: Set transient for parent

This was accidentally removed in d9a0c7d15a.

* gpodderchannel.ui: Downgrade GTK requirement to 3.16

* README.md: Increase minimum GTK version to 3.16

README.md

@@ -43,7 +43,7 @@ PyPI. With this, you get a self-contained gPodder CLI codebase.
 ### GTK3 UI - Additional Dependencies
 
 - [PyGObject](https://wiki.gnome.org/PyGObject) 3.22.0 or newer
-- [GTK+3](https://www.gtk.org/) 3.10 or newer
+- [GTK+3](https://www.gtk.org/) 3.16 or newer
 
 
 ### Optional Dependencies

share/gpodder/ui/gtk/gpodderchannel.ui

@@ -1,7 +1,7 @@
 <?xml version="1.0" encoding="UTF-8"?>
 <!-- Generated with glade 3.38.2 -->
 <interface>
-  <requires lib="gtk+" version="3.20"/>
+  <requires lib="gtk+" version="3.16"/>
   <object class="GtkDialog" id="gPodderChannel">
     <property name="can-focus">False</property>
     <property name="title" translatable="yes">Channel Editor</property>

src/gpodder/gtkui/desktop/podcastdirectory.py

@@ -99,6 +99,7 @@ class DirectoryProvidersModel(Gtk.ListStore):
 
 class gPodderPodcastDirectory(BuilderWidget):
     def new(self):
+        self.gPodderPodcastDirectory.set_transient_for(self.parent_widget)
         if hasattr(self, 'custom_title'):
             self.main_window.set_title(self.custom_title)
 

src/gpodder/gtkui/desktop/preferences.py

@@ -185,6 +185,7 @@ class gPodderPreferences(BuilderWidget):
     C_TOGGLE, C_LABEL, C_EXTENSION, C_SHOW_TOGGLE = list(range(4))
 
     def new(self):
+        self.gPodderPreferences.set_transient_for(self.parent_widget)
         for cb in (self.combo_audio_player_app, self.combo_video_player_app):
             cellrenderer = Gtk.CellRendererPixbuf()
             cb.pack_start(cellrenderer, False)