Yes it is a shared resource, but that doesn't mean that none of the programs can use their own palette when they are running. When you switch over to another program the OS will switch to the appropriate palette. So yes, the OS does have control of the palette, but it gives each program control over it's own palette and switches when it needs to.
Different programs use different palettes all the time.
This is nothing new. Most of the respondents to my message seem to think that this would be some strange violation of the way things are normally done. This IS the way things are normally done when you are limited to 256 colors at a time. 256 colors does not mean a set palette of 256 colors that all programs must conform to. I agree, however, that this should be something which is set with style sheets.