text surrounding the insertion point, as UTF-8. the preedit string should not be included within @text.
the length of @text, or -1 if @text is nul-terminated
the byte index of the insertion cursor within @text.
Deprecated: Use [method@Gtk.IMContext.set_surrounding_with_selection] instead
Sets surrounding context around the insertion point and preedit string.
This function is expected to be called in response to the [signal@Gtk.IMContext::retrieve-surrounding] signal, and will likely have no effect if called at other times.