fembooru/themes/warm/upload.theme.php

<?php

class CustomUploadTheme extends UploadTheme {
	public function display_block(Page $page) {
		$page->add_block(new Block("Upload", $this->build_upload_block(), "head", 20));
	}

	public function display_full(Page $page) {
		$page->add_block(new Block("Upload", "Disk nearly full, uploads disabled", "head", 20));
	}
}