This message works only for notebooks with the style BKS_TABBEDDIALOG. The colors set by BKV_AUTOTABCOLORS are as follows: 0x0055DBFF 0x0080DBAA 0x008092FF 0x00D5B6AA 0x00FFFFAA
0x00AA92AA 0x00FF9255 0x00FFDB55 0x00FFB6AA 0x00FFDBAA
In 16-color mode, or when the Palette Manager is active in 256-color mode, notebooks that are in auto-color mode switch to a set of dithered colors, making sure that the tab text is readable.

The application can change the color of the tab again by sending additional BKM_SETTABCOLOR messages for the specified page.

If the page ID specified in the ulPageId is zero, all the tabs are set to the specified color.