Haiku has something wrong at the bottom of screen

I’v installed Haiku to an old PC (BIOS, intel E2140, 2G RAM, 500G hard disk), and succeded. Haiku used the correct screen resolution, recognized the network device. One problem is, when I move the cursor or a window close to the bottom of screen, something strange appears at the bottom. First screenshot shows a normal situation, and the second shows what happened incorrectly.



Anyone has some opinions? Thanks.

This looks like a bug!
Better to report it here: https://dev.haiku-os.org/