diff --git a/gerrit-prettify/src/main/java/com/google/gerrit/prettify/common/PrettyFormatter.java b/gerrit-prettify/src/main/java/com/google/gerrit/prettify/common/PrettyFormatter.java
index e862e66..c5a8b27 100644
--- a/gerrit-prettify/src/main/java/com/google/gerrit/prettify/common/PrettyFormatter.java
+++ b/gerrit-prettify/src/main/java/com/google/gerrit/prettify/common/PrettyFormatter.java
@@ -441,14 +441,18 @@
 
   private SafeHtml showTabAfterSpace(SafeHtml src) {
     final String m = "( ( |<span[^>]*>|</span>)*\t)";
-    final String r = "<span class=\"wse\">$1</span>";
+    final String r = "<span class=\"wse\"" //
+        + " title=\"" + PrettifyConstants.C.wseTabAfterSpace() + "\"" //
+        + ">$1</span>";
     src = src.replaceFirst("^" + m, r);
     src = src.replaceAll("\n" + m, "\n" + r);
     return src;
   }
 
   private SafeHtml showTrailingWhitespace(SafeHtml src) {
-    final String r = "<span class=\"wse\">$1</span>$2";
+    final String r = "<span class=\"wse\"" //
+        + " title=\"" + PrettifyConstants.C.wseTrailingSpace() + "\"" //
+        + ">$1</span>$2";
     src = src.replaceAll("([ \t][ \t]*)(\r?(</span>)?\n)", r);
     src = src.replaceFirst("([ \t][ \t]*)(\r?(</span>)?\n?)$", r);
     return src;
diff --git a/gerrit-prettify/src/main/resources/com/google/gerrit/prettify/client/gerrit.css b/gerrit-prettify/src/main/resources/com/google/gerrit/prettify/client/gerrit.css
index 86f53d6..85276ae 100644
--- a/gerrit-prettify/src/main/resources/com/google/gerrit/prettify/client/gerrit.css
+++ b/gerrit-prettify/src/main/resources/com/google/gerrit/prettify/client/gerrit.css
@@ -21,6 +21,7 @@
 
 .wse {
   background: red;
+  cursor: pointer;
 }
 
 .vt {