I took some time over the holidays to clean up GtkHtml's code a bit.  The patch turned out to be ~5000 lines, so my apologies in advance to whomever winds up reviewing this.

Here's what I changed [1]:


- Fix (almost) all compiler warnings.

    Obsoletes bug #363036.

    Excludes warnings caused by bug #363033.


- Stop using deprecated GTK+ widgets and symbols.

    NOTE: There's still a few spots where deprecated GTK+ symbols are
          being used, so we can't compile with -DGTK_DISABLE_DEPRECATED
          just yet.  In particular, construction of the editor's toolbar
          involves calls to things like gtk_toolbar_append_widget().
	  Also, htmlselect.c uses the deprecated GtkCombo widget, but I
          don't yet understand that code well enough mess with it.

    Use GtkComboBox instead of GtkOptionMenu [2].

    Use g_object_force_floating() instead of GTK_OBJECT_SET_FLAGS().

    Use g_object_is_floating() instead of GTK_OBJECT_FLOATING().

    Use g_object_ref_sink() instead of gtk_object_sink().

    Use g_idle_add() instead of gtk_idle_add().

    Use g_timeout_add() instead of gtk_timeout_add().

    Use g_source_remove() instead of gtk_idle_remove().

    Use g_source_remove() instead of gtk_timeout_remove().

    Use gtk_widget_set_size_request() instead of gtk_widget_set_usize().

    Use gtk_window_set_resizable() instead of gtk_window_set_policy().


- Stop using _some_ deprecated libgnomeui widgets and symbols.

    Use GtkColorButton instead of GnomeColorPicker.

    Use gtk_window_set_icon_name() instead of
        gnome_window_icon_set_from_file().


- Stop including <gnome.h>

    <gnome.h> includes <libgnomeui/libgnomeui.h> which in turn uses
    the deprecated GtkCombo widget.  In many cases, <gtk/gtk.h> is all
    that's really needed.  When libgnomeui symbols are needed, include
    only the necessary header files (e.g. <libgnomeui/gnome-app-helper.h>).


- Prefer stock or named icons.

    GtkHtml still distributes many icon files that are now provided by
    gnome-icon-theme.  The following is a list of GtkHtml icon files and
    their equivalent stock or named icons which are now used in the code.
    I removed these icon files from art/Makefile.am so they will no longer
    be distributed, and I propose removing them from Subversion as well.

      GtkHtml Icon File                 Replaced With
      ------------------------------    ------------------------------
      art/16_copy.png                   GTK_STOCK_COPY
      art/24_copy.png                   GTK_STOCK_COPY
      art/16_cut.png                    GTK_STOCK_CUT
      art/24_cut.png                    GTK_STOCK_CUT
      art/16_paste.png                  GTK_STOCK_PASTE
      art/24_paste.png                  GTK_STOCK_PASTE
      art/font-tt-16.png                "stock_text-monospaced"
      art/font-tt-24.png                "stock_text-monospaced"
      art/insert-image-16.png           "stock_insert_graphic"
      art/insert-image-24.png           "stock_insert_graphic"
      art/insert-link-16.png            "stock_insert-url"
      art/insert-link-24.png            "stock_insert-url"
      art/insert-object-16.png          "stock_insert_graphic"
      art/insert-object-24.png          "stock_insert_graphic"
      art/insert-rule-16.png            "stock_insert-rule"
      art/insert-rule-24.png            "stock_insert-rule"
      art/insert-table-16.png           "stock_insert-table"
      art/insert-table-24.png           "stock_insert-table"
      art/properties-16.png             GTK_STOCK_PROPERTIES
      art/redo-16.png                   GTK_STOCK_REDO
      art/redo-24.png                   GTK_STOCK_REDO
      art/search-16.png                 GTK_STOCK_FIND
      art/search-24.png                 GTK_STOCK_FIND
      art/search-and-replace-16.png     GTK_STOCK_FIND_AND_REPLACE
      art/search-and-replace-24.png     GTK_STOCK_FIND_AND_REPLACE
      art/smiley-1.png                  "stock_smiley-6"
      art/smiley-2.png                  "stock_smiley-5"
      art/smiley-3.png                  "stock_smiley-1"
      art/smiley-4.png                  "stock_smiley-3"
      art/smiley-5.png                  "stock_smiley-2"
      art/smiley-6.png                  "stock_smiley-4"
      art/smiley-8.png                  "stock_smiley-8"
      art/smiley-9.png                  "stock_smiley-9"
      art/smiley-10.png                 "stock_smiley-10"
      art/smiley-11.png                 "stock_smiley-11"
      art/smiley-12.png                 "stock_smiley-26"
      art/table-column-16.png           "stock_select-column"
      art/table-row-16.png              "stock_select-row"
      art/table-table-16.png            "stock_select-table"
      art/undo-16.png                   GTK_STOCK_UNDO
      art/undo-24.png                   GTK_STOCK_UNDO


[1] The capplet code appears to be dead.  It's not distributed in GtkHtml
    releases, and the latest capplet/ChangeLog entry is dated 2004-07-22.
    Therefore I didn't bother with it.  This bug only applies to the
    libgtkhtml and html-editor source code.

[2] The paragraph style combo box was particularly fun to migrate.
    Since some of its items are desensitized when in plaintext mode,
    a simple text combo box won't do.  Instead, we have to set up a
    two-column list store to populate the combo box widgets and manage
    the sensitivity of their items.  I wound up splitting the logic
    for this widget into new source files:

        components/html-editor/paragraph-style.[ch]