The following will tell you whether or not all of the text is selected within a text input in all major browsers.
Example: http://www.jsfiddle.net/9Q23E/
Code:
function isTextSelected(input) {
if (typeof input.selectionStart == "number") {
return input.selectionStart == 0 && input.selectionEnd == input.value.length;
} else if (typeof document.selection != "undefined") {
input.focus();
return document.selection.createRange().text == input.value;
}
}