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Under some conditions, all of the icons in the Program Manager under Windows 3.x turn black

Explanation: Occasionally while using the Program Manager under Windows 3.x, I observe that all of the icons in a program group will turn totally black. There seems to be no other problems with the video and nothing seems to fix the icons.

Diagnosis: This problem is caused by poor software design: it is the combination of a limitation in how memory works under Windows 3.x, and a limitation in the way icons are allocated memory by the Program Manager. The problem is exacerbated by running with a high color depth, so it is seen more when running in high color or true color mode than 256-color mode. What happens is this. Windows 3.x allows only 64 KB to hold all of the images in a Program Manager group. The size of these icons is 32 pixels by 32 pixels, which means a total of 1,024 pixels. If you are using a color depth of one byte per pixel (256-color mode) then each icon takes 1 KB, and you could have just under 64 of them without a problem in any group (some memory is taken up by overhead so you couldn't have exactly 64). However, if you run in true color mode, 24 bits of color information per pixel, then each icon takes up 3,072 bytes of information. This is true no matter how many different colors are actually used in the icon! This limits you to only about 20 icons per Program Manager group. If you then have more than 20 icons in a group, all of the color information cannot be retained and the icons will be drawn as black squares.

Recommendation: Try the following:

  • Split larger Program Manager groups into multiple, smaller groups. This is the simplest way to avoid the problem.
  • If you are running in true color mode (24 bit color) or high color mode (16 bit color) then consider running in 256-color mode instead. This is not a good solution for everyone, since there are good reasons to run at higher color depths.
  • Upgrade your operating system to Windows 95, which does not have this problem (of course there are many issues involved in making such a decision).

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