+/*
+First some explanation about what a Cursor really is, from local to
+global.
+
+* a CursorSlice indicates the position of the cursor at local level.
+ It contains in particular:
+ * idx(): the cell that contains the cursor (for Tabular or math
+ arrays). Always 0 for 'plain' insets
+ * pit(): the index of the current paragraph (only for text)
+ * pos(): the position in the current paragraph (or in the math
+ equation in mathed).
+ * inset(): the inset in which the cursor is. For a InsetTabular,
+ this is the tabular itself, not the cell inset (which is an
+ InsetTableCell).
+
+* a DocIterator indicated the position of the cursor in the document.
+ It knows about the current buffer (buffer() method) and contains a
+ vector of CursorSlices that describes the nesting of insets up to the
+ point of interest. Note that operator<< has been implemented, so that
+ one can send a DocIterator to a stream to see its value. Try it, it is
+ very helpful to understand the cursor layout.
+ * when using idx/pit/pos on a DocIterator, one gets the information
+ from the inner slice (this slice can be accessed as top())
+ * inMathed() returns true when the cursor is in a math formula
+ * inTexted() returns true when the cursor is in text
+ * innerTextSlice() returns the deepest slice that is text (useful
+ when one is in a math equation and looks for the enclosing text)
+
+* A CursorData is a descendant of Dociterator that contains
+ * a second DocIterator object, the anchor, that is useful when
+ selecting.
+ * some other data that describes current selection, cursor font, etc.
+
+ This class is mostly used only for undo and contains the Cursor
+ elements that are not GUI-related. In LyX 2.0, Cursor was directly
+ deriving from DocIterator
+
+* A Cursor is a descendant of CursorData that contains interesting
+ display-related information, in particular targetX(), the horizontal
+ position of the cursor in pixels.
+*/
+