AlbumButtonBox: add visual cue to indicate a filter is active

templates/AlbumButtonBox.php

@@ -33,7 +33,16 @@ class AlbumButtonBox extends Template
 			echo '
 				<div class="dropdown">
 					<button class="btn btn-light dropdown-toggle" type="button" data-bs-toggle="dropdown" aria-expanded="false">
-						<i class="bi bi-filter"></i>
+						<i class="bi bi-filter"></i>';
+
+			if ($this->active_filter)
+			{
+				echo '
+						<span class="badge text-bg-danger">',
+							$this->filters[$this->active_filter]['label'], '</span>';
+			}
+
+			echo '
 					</button>
 					<ul class="dropdown-menu">';