
4 answers
That is not possible using off the shelf settings, Formulas, Workflows, etc, for that you'll need custom Apex Code. Otherwise you might want to look into the (free) Agent Console or (paid) Sales Console Tab => https://help.salesforce.com/HTViewHelpDoc?id=console_about.htm&language=en_US (https://help.salesforce.com/HTViewHelpDoc?id=console_about.htm&language=en_US)
Or (possibly) the Process Builder