Instead, keep a list of tags to explicitely remove around (the list of
unchecked toggles), and remove only these tags, so the tags that have
no widget in the UI are not affected by the insert_tags logic.
Use gtk_text_buffer_begin_user_action() and end_user_action() to group
all text buffer operations triggered by a single editing operation.
Connect to the buffer's "end-user-action" signal instead of to
"changed", "apply-tag" and "remove-tag" separately, so we only update
the text proxy once per user editing.
instead of using the toggles only to change the style of selected text.
Introduces a list of "insert tags" in GimpTextBuffer that is applied
on newly inserted text if it exists. Clear the list on each content
or cursor/selection change, so we always display wthe style at the
cursor unless the buttons were clicked explicitely.
- keep around tags for styles in GimpTextBuffer. For now only bold,
italic, underline and strikethrough.
- add GimpTextStyleEditor, a widget which allows setting tags on
a GimpTextBuffer's selection.
- add serialize/deserialize code to/from pango markup using
GtkTextBuffer's rich text (de)serialization infrastructure.
Doesn't produce or handle <span> yet.
