El búfer

To specify that some text in the buffer should have specific formatting, you must define a tag to hold that formatting information, and then apply that tag to the region of text. For instance, to define the tag and its properties:

Glib::RefPtr<Gtk::TextBuffer::Tag> refTagMatch =
    Gtk::TextBuffer::Tag::create();
refTagMatch->property_background() = "orange";

You can specify a name for the Tag when using the create() method, but it is not necessary.

The Tag class has many other properties.

Referencia

Each Gtk::TextBuffer uses a Gtk::TextBuffer::TagTable, which contains the Tags for that buffer. 2 or more TextBuffers may share the same TagTable. When you create Tags you should add them to the TagTable. For instance:

Glib::RefPtr<Gtk::TextBuffer::TagTable> refTagTable =
    Gtk::TextBuffer::TagTable::create();
refTagTable->add(refTagMatch);
//Posiblemente, la siguiente versión de gtkmm tenga un método set_tag_table(),
//para usarlo después de la creación del búfer.
Glib::RefPtr<Gtk::TextBuffer> refBuffer =
    Gtk::TextBuffer::create(refTagTable);

You can also use get_tag_table() to get, and maybe modify, the TextBuffer's default TagTable instead of creating one explicitly.

Referencia

If you have created a Tag and added it to the TagTable, you may apply that tag to part of the TextBuffer so that some of the text is displayed with that formatting. You define the start and end of the range of text by specifying Gtk::TextBuffer::iterators. For instance:

refBuffer->apply_tag(refTagMatch, iterRangeStart, iterRangeStop);

Or you could specify the tag when first inserting the text: refBuffer->insert_with_tag(iter, "Some text", refTagMatch);

You can apply more than one Tag to the same text, by using apply_tag() more than once, or by using insert_with_tags(). The Tags might specify different values for the same properties, but you can resolve these conflicts by using Tag::set_priority().

TextView has various methods which allow you to change the presentation of the buffer for this particular view. Some of these may be overridden by the Gtk::TextTags in the buffer, if they specify the same things. For instance, set_left_margin(), set_right_margin(), set_indent(), etc.

Gtk::TextView has various scroll_to_*() methods. These allow you to ensure that a particular part of the text buffer is visible. For instance, your application's Find feature might use Gtk::TextView::scroll_to_iter() to show the found text.