Obtains the position of the PangoLayout used to
render text in the entry, in widget coordinates. Useful if you want to
line up the text in an entry with some other text, e.g. when using the
entry to implement editable cells in a sheet widget.
Also useful to convert mouse events into coordinates inside the
PangoLayout, e.g. to take some action if some
part of the entry text is clicked.
Note that as the user scrolls around in the entry the offsets will
change. Remember when using the PangoLayout functions you need to convert
to and from pixels using PANGO_PIXELS() or PANGO_SCALE.
The returned value is array($x, $x).