How to make Comments screen as a mandatory while releasing the Documents

Hi,

How can we do the Comments screen as a mandatory when Releasing Document/Business Partenr in GTS.

Explanation: When we Manually Release Blocked Documents, It will ask the comments to enter the reason for unblock. here we can save without entering any Comments or we can save by pressing the cancel button on the comments screen. here we need to make this comments screen as a Mandatory. so everyone who is releasing the document should enter the Comments

Thanks

Ram