Change workitem text in SWBP.

Hello.

I would like to know what control the possibility to change the workitem text for tasks in the workflow inbox (SWBP). If you select a task in your inbox and click on the "Other Functions" button (10th button from left) a roll down menu appears where the last line says "Change Work Item Text". This line is grey. What controls it? How to make it a valid input?

Thanks.

Lande