How to trigger “Select All Unused” flyoutmenu of “Swatches Panel” in illustrator sdk using c++

This post on this forum isn't specifically about swatches, but will show you how to create and run a path offset action on the fly.

The SDK header AIActionManager.h has a lot of helpful information in it, as well as the Tutorial project in the SDK sample code.

If you record your menu selection as an action, then save the actions and open your .aia file, you can see the values the action manager needs.

/action-28 {
/name [ 11
737761746368206d656e75
]
/keyIndex 0
/colorIndex 0
/isOpen 1
/eventCount 1
/event-1 {
/useRulersIn1stQuadrant 0
/internalName (ai_plugin_swatches)
/localizedName [ 8
5377617463686573
]
/isOpen 0
/isOn 1
/hasDialog 0
/parameterCount 1
/parameter-1 {
/key 1835363957
/showInPalette 4294967295
/type (enumerated)
/name [ 17
53656c65637420416c6c20556e75736564
]
/value 11
}
}
}

In the "name" field, note that 53656c65637420416c6c20556e75736564 translates from hex to ascii as "Select All Unused"

I haven't tested this code, but it should at least give you a good start. I use a lot of std::string, but you'll likely want to use char* instead.

AIActionParamValueRef param;
AIErr error = kNoErr;
ActionParamKeyID key(1835363957);
std::string val("Select All Unused");
error = sAIAction->AINewActionParamValue(&param);
error = sAIAction-> AIActionSetEnumerated(param, key, val.c_str(), 11);
error = sAIAction->PlayActionEvent("ai_plugin_swatches", kDialogOff, param);
error = sAIAction->AIDeleteActionParamValue(param);