Rocket.Chat/app/message-action/client/messageAction.html

<template name="messageAction">
	<div class="action  {{#if areButtonsHorizontal}}horizontal-buttons{{/if}}">
		{{#if isButton}}
			{{#if image_url}}
				{{#if url}}
					<a href="{{url}}" target="_blank" type="button" rel="noopener noreferrer">
						<img class="image-button" src="{{image_url}}"/>
					</a>
				{{/if}}

				{{#if msg_in_chat_window}}
					<button class="{{jsActionButtonClassname msg_processing_type}}" value="{{msg}}">
						<img class="image-button" src="{{image_url}}" />
					</button>
				{{/if}}
			{{/if}}
			{{#if text}}
				{{#if url}}
					<a class="text-button" href="{{url}}" target="_blank" type="button" rel="noopener noreferrer">
						<span class="overflow-ellipsis">{{text}}</span>
					</a>
				{{/if}}
				{{#if msg_in_chat_window}}
					<button class="text-button {{jsActionButtonClassname msg_processing_type}}" value="{{msg}}">
						<span class="overflow-ellipsis">{{text}}</span>
					</button>
				{{/if}}
			{{/if}}
		{{/if}}
	</div>
</template>