I do not know if it is a bug or not, but I think is because you access the .value property and each time the .value property is accessed, it seems that resets the .selstart property. But, I am not sure, I just saw your code and tried it, and while typing in the textbox to check it, I saw that behaviour and thought of a workaround, I leave all bug reports to Fabio <g>
"The five senses obstruct or deform the apprehension of reality."
Jorge L. Borges?
"Premature optimization is the root of all evil in programming."
Donald Knuth, repeating C. A. R. Hoare
"To die for a religion is easier than to live it absolutely"
Jorge L. Borges