forgejo/templates/repo/issue/comment_tab.tmpl

<div class="ui top tabular menu" data-write="write" data-preview="preview">
	<a class="active item" data-tab="write">{{.i18n.Tr "write"}}</a>
	<a class="item" data-tab="preview" data-url="{{.Repository.APIURL}}/markdown" data-context="{{.RepoLink}}">{{.i18n.Tr "preview"}}</a>
</div>
<div class="field">
	<div class="ui bottom active tab" data-tab="write">
		<textarea id="content" class="edit_area js-quick-submit" name="content" tabindex="4" data-id="issue-{{.RepoName}}" data-url="{{.Repository.APIURL}}/markdown" data-context="{{.Repo.RepoLink}}">
			{{- if .BodyQuery}}{{.BodyQuery}}{{else if .IssueTemplate}}{{.IssueTemplate}}{{else if .PullRequestTemplate}}{{.PullRequestTemplate}}{{else}}{{.content}}{{end -}}
		</textarea>
	</div>
	<div class="ui bottom tab markup" data-tab="preview">
		{{.i18n.Tr "loading"}}
	</div>
</div>
{{if .IsAttachmentEnabled}}
	<div class="field">
		{{template "repo/upload" .}}
	</div>
{{end}}