onSelectStart
The instruction(s) to be executed are placed within quotes. This event handler will execute the instruction(s) when the user has started to select the element.

The following example will display text of your choosing in a message box when the user has started to select the element:
onSelectStart="msgWindow.document.write('-- Insert text message here --')"
This Event Handler is used with the following:

A
ACRONYM
ADDRESS
B
BIG
BLOCKQUOTE
BODY
BUTTON
CAPTION
CENTER
CITE
CODE
DD
DEL
DFN
DIR
DIV
DL
DT
EM
FIELDSET
FONT
FORM
H1
H2
H3
H4
H5
H6
I
IMG
INS
KBD
LABEL
LEGEND
LI
LISTING
MARQUEE
MENU
OBJECT
OL
P
PLAINTEXT
PRE
Q
S
SAMP
SELECT
SMALL
SPAN
STRIKE
STRONG
SUB
SUP
TABLE
TBODY
TD
TEXTAREA
TFOOT
THEAD
TR
TT
U
UL
VAR
XMP