android:fadeScrollbars

added in API Level 5

Defines whether to fade out scrollbars when they are not in use.

Doesn't seem to do anything with TextView or EditText.
Textview and HoriztonalScrollview, does nothing with fadeScrollbars
EditText and scrollHorizontally, does nothing with fadeScrollbars

android:fadeScrollbars = "true"
android:fadeScrollbars = "false"

Resources:
http://developer.android.com/reference/android/view/View.html#attr_android:fadeScrollbars
http://developer.android.com/reference/android/R.attr.html#fadeScrollbars