A bug in CExtPopupColorMenuWnd::_DoPaint prevents a colour defined as 32-bit from being drawn properly in the popup window. The bug was found in Prof 2.9.2, but I have looked at the source code for 3.0.1 and it appears to still be an issue.
The following is the fix (around line 21812 of ExtPopupMenuWnd.cpp v3.0.1):
This:
_ppbd.m_bHelperColorCellButton = true;
PmBridge_GetPM()->PaintPushButton( dc, _ppbd );
rcItem.DeflateRect( _sizeColorItemSpaces.cx, _sizeColorItemSpaces.cy );
dc.FillSolidRect( &rcItem, _GetColorValue( nIdx ) );
dc.Draw3dRect( &rcItem, clrColorBorder,clrColorBorder );
Should be changed to this:
_ppbd.m_bHelperColorCellButton = true;
PmBridge_GetPM()->PaintPushButton( dc, _ppbd );
rcItem.DeflateRect( _sizeColorItemSpaces.cx, _sizeColorItemSpaces.cy );
const COLORREF fillColour = _GetColorValue(nIdx) & ~0xFF000000;
dc.FillSolidRect( &rcItem, fillColour );
dc.Draw3dRect( &rcItem, clrColorBorder,clrColorBorder );