>If a programmer purposely changes the BackColor property to an explicit color, I'm sure he knows and intends this color to be consistent throughout his app no matter what the user's Windows desktop color scheme.

No one has mentioned what I consider the key point in the thread. This is an accessibility issue. The reality is that you shouldn't be setting colors anywhere in your application unless you explicitly use the API to dig up the colors from the user's current color scheme. Some users have very specific Windows color schemes designed to give them maximum readability in spite of visual disabilities. Anytime you hard-code a color in a app, you run the risk of disenfranchising those users.

Don't think that the number of users with disabilities is small, either. Overall, about 20% of the US population has at least one disability (including such things as reduced vision, color blindness, limited hearing, and mobility impairments). The disability rate increases with age.

Along the same lines, using a bitmap instead of a button means that that color may not be available to blind users because a screen reader application would be able to read it to them.

For almost all applications (and especially including any you want to sell to the US government or any US business with 50 or more employees), the right answer is to go with the flow. Let users determine colors, not developers.

Tamar