Increase the z-index of the select area in the drive

www/drive/file.css

@@ -231,6 +231,7 @@ span.fa-folder-open {
   display: none;
   background-color: rgba(100, 100, 100, 0.7);
   position: absolute;
+  z-index: 50;
 }
 #content.readonly {
   background: #e6e6e6;

www/drive/file.less

@@ -275,6 +275,7 @@ span {
         display: none;
         background-color: rgba(100, 100, 100, 0.7);
         position: absolute;
+        z-index: 50;
     }
     &.readonly {
         background: @content-bg-ro;