text in this.
Like [method@Gtk.TextBuffer.insert], but the insertion will not occur if
iter is at a non-editable location in the buffer. Usually
you want to prevent insertions at ineditable locations if the insertion results from a user action (is interactive).
default_editable indicates the editability of text that doesn't have a tag affecting editability applied to it. Typically the
result of [method@Gtk.TextView.get_editable] is appropriate here.
a position in this
some UTF-8 text
length of text in bytes, or -1
default editability of buffer
whether text was actually inserted