Gnome-tweak-tool issues

[les]

I have added gnome-tweak-tool to my system.  However I have some
problems with it.  First run from the software install tool went OK.  
	Made changes to various fonts, and they took effect.

	However on subsequent runs I had to start it from the command line, and
it hung up, but I also got a few warnings and errors which are listed
below.

	Is there any package I need to install to overcome these issues?



Second and subsequent runs:
$ gnome-tweak-tool
WARNING : Schema /usr/share/glib-2.0/schemas/org.gnome.shell.gschema.xml
missing summary text: <key name="saved-im-presence" type="i">
      <default>1</default>
      <summary/>
    </key>
WARNING : Schema /usr/share/glib-2.0/schemas/org.gnome.shell.gschema.xml
missing summary text: <key name="saved-session-presence" type="i">
      <default>0</default>
      <summary/>
    </key>

(gnome-tweak-tool:2166): Gtk-CRITICAL **:
gtk_widget_get_preferred_height_for_width: assertion `width >= 0' failed

(gnome-tweak-tool:2166): Gtk-CRITICAL **:
gtk_widget_get_preferred_height_for_width: assertion `width >= 0' failed

(gnome-tweak-tool:2166): Gtk-CRITICAL **:
gtk_widget_get_preferred_height_for_width: assertion `width >= 0' failed

(gnome-tweak-tool:2166): Gtk-CRITICAL **:
gtk_widget_get_preferred_height_for_width: assertion `width >= 0' failed

(gnome-tweak-tool:2166): Gtk-CRITICAL **:
gtk_widget_get_preferred_height_for_width: assertion `width >= 0' failed

(gnome-tweak-tool:2166): Gtk-CRITICAL **:
gtk_widget_get_preferred_height_for_width: assertion `width >= 0' failed

(gnome-tweak-tool:2166): Gtk-CRITICAL **:
gtk_widget_get_preferred_height_for_width: assertion `width >= 0' failed

(gnome-tweak-tool:2166): Gtk-CRITICAL **:
gtk_widget_get_preferred_height_for_width: assertion `width >= 0' failed

(gnome-tweak-tool:2166): Gtk-CRITICAL **:
gtk_widget_get_preferred_height_for_width: assertion `width >= 0' failed

(gnome-tweak-tool:2166): Gtk-CRITICAL **:
gtk_widget_get_preferred_height_for_width: assertion `width >= 0' failed

(gnome-tweak-tool:2166): Gtk-CRITICAL **:
gtk_widget_get_preferred_height_for_width: assertion `width >= 0' failed

(gnome-tweak-tool:2166): Gtk-CRITICAL **:
gtk_widget_get_preferred_height_for_width: assertion `width >= 0' failed

(gnome-tweak-tool:2166): Gtk-CRITICAL **:
gtk_widget_get_preferred_height_for_width: assertion `width >= 0' failed

(gnome-tweak-tool:2166): Gtk-CRITICAL **:
gtk_widget_get_preferred_height_for_width: assertion `width >= 0' failed

(gnome-tweak-tool:2166): Gtk-CRITICAL **:
gtk_widget_get_preferred_height_for_width: assertion `width >= 0' failed