A position in a GtkTextBuffer which persists across buffer modifications.
By default, every buffer automatically creates two GtkTextMarks named insert and selection_boud. They point to the insertion point (cursor) and the selection boundry which is not the insertion point, respectively. Moving these two marks to two different places in the buffer will select the range of text between them. Both marks have right gravity.
get_buffer() Returns the GtkTextBuffer that the mark belongs to. get_deleted() Returns whether or not the mark has been deleted from its GtkTextBuffer. get_left_gravity() Returns whether or not the mark has left gravity. get_name() Returns the name of the mark, or null if the mark is anonymous. get_visible() Returns whether or not a cursor is shown for the mark. set_visible() Sets whether or not a cursor should be shown for the mark.