Compare value.

src/compare/diff.rs

@@ -2273,8 +2273,6 @@ fn compare_fixed_width_area<'b, 's>(
     let mut this_status = DiffStatus::Good;
     let mut message = None;
 
-    // TODO: Compare :value
-
     // TODO: Compare :caption
     // Compare name
     let name = get_property_quoted_string(emacs, ":name")?;
@@ -2286,6 +2284,18 @@ fn compare_fixed_width_area<'b, 's>(
         ));
     }
 
+    // Compare value
+    let value = get_property_quoted_string(emacs, ":value")?
+        .ok_or("Fixed width area should have a value.")?;
+    let rust_value = rust.get_value();
+    if value != rust_value {
+        this_status = DiffStatus::Bad;
+        message = Some(format!(
+            "Value mismatch (emacs != rust) {:?} != {:?}",
+            value, rust_value
+        ));
+    }
+
     Ok(DiffResult {
         status: this_status,
         name: rust.get_elisp_name(),