A position in a GtkTextBuffer which persists across buffer modifications.
A GtkTextMark is used to identify a location within
a GtkTextBuffer. Unlike a
GtkTextIter, a GtkTextMark
will persist across buffer modifications.
A GtkTextMark cannot be instantiated directly with
the new operator. Instead it must be created using
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.