I have a button to choose from my tab groups Go TABGROUPlist=icons. I removed some old icon libraries, and now the group icons show as smiley faces. The icon for the button (which only appears in customized mode) is the tabs icon from the "Directory Opus 9" icon set. I thought the "child" icons came from the "parent".
That's a bug; Opus is using the wrong icon name for the generated buttons.
It'll be fixed in the next update.