Show always the checkbox

The checkbox is not shown always with full opacity, though, in order to
reduce the visual noise (specially later, once the checkbox is moved to
its own column).

Signed-off-by: Daniel Calviño Sánchez <danxuliu@gmail.com>

apps/files/css/files.scss

@@ -441,14 +441,14 @@ table td.filename .uploadtext {
 
 /* File checkboxes */
 #fileList tr td.filename>.selectCheckBox + label:before {
-	opacity: 0;
+	opacity: 0.3;
 	position: absolute;
 	bottom: 4px;
 	right: 0;
 	z-index: 10;
 }
 
-/* Show checkbox when hovering, checked, or selected */
+/* Show checkbox with full opacity when hovering, checked, or selected */
 #fileList tr:hover td.filename>.selectCheckBox + label:before,
 #fileList tr:focus td.filename>.selectCheckBox + label:before,
 #fileList tr td.filename>.selectCheckBox:checked + label:before,