Lightning modal dialog from a list custom button

Question

Is it possible, from a related list, to have a custom button that opens a lightning modal dialog, as is the behavior of the standard buttons of these related lists?

My research tells me that it isn't possible given that the onclick JavaScript buttons are no longer allowed in the Lightning experience but would like to confirm this with you.

Here are some pictures to show better what I want.

Answer 1

With the new Winter 17 release you can Launch a Lightning Component from an Action

So if your modal would be this lightning component, you can launch it as an action

Answer 2

Quick Actions cannot be used as Related List Buttons: Upvote Idea here, so unfortunately response by Itai is not a complete answer.

The best I have found is to give up on using a related list button for a modal and instead use Lightning Component Action like Itai referenced. Unfortunately the force:LightningQuickAction and force:LightningQuickActionWithoutHeader interfaces display a thin modal that can't be widened.

Solution for a wider modal is to create two Lightning Components: 1. one that implements force:LightningQuickAction and force:LightningQuickActionWithoutHeader to launch from the Action, and 2. one that is launched as another modal from the first Lightning Component using lightning:overlayLibrary and then closes the Quick Action modal.

Example code:

Component:

<aura:component implements="force:hasRecordId,force:LightningQuickActionWithoutHeader">
    <aura:attribute name="recordId" type="String"/>
    <aura:handler name="init" value="{!this}" action="{!c.onInit}"/>
    <lightning:overlayLibrary aura:id="overlayLib"/>
</aura:component>

Controller:

({
    onInit : function(component, event, helper) {
        // Launch actual target modal
        $A.createComponent("c:CampaignMemberWizard", {
            recordId : component.get("v.recordId")
        },
        function(content, status) {
            if (status === "SUCCESS") {
                component.find('overlayLib').showCustomModal({
                    body: content,
                    showCloseButton: true,
                    cssClass: "slds-modal_large",
                    closeCallback: function () {
                        // Nothing needed for this component
                    }
                })
            }
        });
        // Close quick action modal
        // If done synchronously, closes both modals
        setTimeout($A.getCallback(function () {
            $A.get("e.force:closeQuickAction").fire();
        }), 100)
    }
});