How do I insert a text into textarea at cursor pos at leave here the cursor ?

How do I insert a text into textarea at cursor pos at leave here the cursor ?

I've a button. I need to provide this to my users:

- User clicks it, I
- my code add some text at cursor position into a textarea
- then the cursor must be STILL HERE, before or after inserted text.

How !?

I googled and seen createTextRange, but FF and Opera have some difficult
Is there a jQuery-way ?