Display Problems in Mouse Demo with 640x480 256-Color Drivers

• Microsoft Mouse Driver for Windows, version 9.0
• Microsoft Windows operating system version 3.1

SYMPTOMS

If you are using a 640 x 480 256-color video driver, horizontal zigzag patterns may appear on the screen when you run the Microsoft Mouse demonstration "Meet The Mouse," which ships with version 9.0 of the mouse driver.

CAUSE

This problem occurs because the source image is a 16-color bitmap and therefore often dithered. When these dithered colors appear on a relatively low-resolution display (such as 640 x 480) that supports 256 colors, horizontal zigzag patterns of alternating colors may appear. This problem is usually intensified by the graying effect, which turns every other pixel to white.

STATUS

Microsoft is researching this problem and will post new information here in the Microsoft Knowledge Base as it becomes available.

MORE INFORMATION

This problem is not normally seen in actual windows (rather than bitmaps of windows) because Microsoft Windows does not dither the colors of actual windows if the display supports them in its palette.