Basically, given a LookAndFeel instance, I’d like to obtain the list of the colour ids that have explicitly been set with LookAndFeel::setColour(), i.e. those for which LookAndFeel::isColourSpecified() would return true.
It’s currently impossible to access that information because the member variable colours that holds them is private to the LookAndFeel class.
Possible implementation, tested and ready to be dropped in juce_LookAndFeel.cpp:
Array <int> LookAndFeel::getSpecifiedColours () const noexcept
{
Array <int> colourIds;
for (const auto& colourSetting : colours)
colourIds.add (colourSetting.colourID);
return colourIds;
}