Phones with the Android operating system use an application called Messaging to manage text messages on the device. Although it is a powerful, full-featured application, you may have chosen to download another messaging application called Handcent to manage all of your text messages. Handcent features a Quick Reply feature that consists of pop-up messages that appear on your phone, thereby allowing you to reply to a message without opening the full application. Although this feature is activated by default, it can be turned off if you so choose.
Unlock your Android phone, and then press the "Home" button to navigate to the phone's home screen.
Touch the "Applications" icon to show your list of installed applications.
Navigate to the "Handcent SMS" icon, and then tap it once to open the application.
Touch the "Menu" button at the bottom of your phone.
Tap the "Settings" option.
Tap "Notification Settings."
Touch the box to the right of "Enable Popup" to remove the check mark and turn off Quick Reply.
If you wish to keep the pop up but want to change how it behaves, touch the "Popup Settings" option after pressing "Notification Settings." From this screen you can set the quickness with which the pop up is displayed as well as configure how the screen will behave when a pop up appears.