In-correct arrow icon on Spinner with custom ArrayAdapter

Refer to the exercise "Custom ArrayAdapter for Spinner, with different icons"; it implement a Spinner with custom ArrayAdapter, base on Build Target of Android 1.6, and android:minSdkVersion="4".

When it run on AVD of Android 2.1, the drop-down arrow on the right side is in-corret.
Run on AVD of Android 2.1

The same code, when it run on AVD of Android 2.3, the arrow is displayed correctly.
Run on AVD of Android 2.3

Up to this minute, I have no any idea on this problem. Sorry for any inconvenience caused!