Creates a mark at position where. If mark_name is NULL, the mark is anonymous; otherwise, the mark can be retrieved by name using TextBuffer.getMark. If a mark has left gravity, and text is inserted at the mark’s current location, the mark will be moved to the left of the newly-inserted text. If the mark has right gravity (left_gravity = FALSE), the mark will end up on the right of newly-inserted text. The standard left-to-right cursor is a mark with right gravity (when you type, the cursor stays on the right side of the text you’re typing).
The caller of this function does not own a reference to the returned gtk.TextMark, so you can ignore the return value if you like. Marks are owned by the buffer and go away when the buffer does.
Emits the mark-set signal as notification of the mark's initial placement.