diff --git a/src/main/java/com/metaweb/gridworks/expr/controls/With.java b/src/main/java/com/metaweb/gridworks/expr/controls/With.java
index d311d1e08..31d41b7a1 100644
--- a/src/main/java/com/metaweb/gridworks/expr/controls/With.java
+++ b/src/main/java/com/metaweb/gridworks/expr/controls/With.java
@@ -43,7 +43,7 @@ public class With implements Control {
 		writer.key("description"); writer.value(
 			"Evaluates expression o and binds its value to variable name v. Then evaluates expression e and returns that result"
 		);
-		writer.key("params"); writer.value("expression o, variable v, expression eNonBlank, expression eBlank");
+		writer.key("params"); writer.value("expression o, variable v, expression e");
 		writer.key("returns"); writer.value("Depends on actual arguments");
 		writer.endObject();
 	}
diff --git a/src/main/java/com/metaweb/gridworks/protograph/Protograph.java b/src/main/java/com/metaweb/gridworks/protograph/Protograph.java
index 236266193..9c553a26e 100644
--- a/src/main/java/com/metaweb/gridworks/protograph/Protograph.java
+++ b/src/main/java/com/metaweb/gridworks/protograph/Protograph.java
@@ -50,11 +50,13 @@ public class Protograph implements Serializable, Jsonizable {
 			String columnName = o.getString("columnName");
 			
 			if ("cell-as-topic".equals(nodeType)) {
-				node = new CellTopicNode(
-					columnName,
-					o.getBoolean("createForNoReconMatch"),
-					reconstructType(o.getJSONObject("type"))
-				);
+				if (o.has("type")) {
+					node = new CellTopicNode(
+						columnName,
+						o.getBoolean("createForNoReconMatch"),
+						reconstructType(o.getJSONObject("type"))
+					);
+				}
 			} else if ("cell-as-value".equals(nodeType)) {
 				node = new CellValueNode(
 					columnName,
diff --git a/src/main/webapp/scripts/project/expression-preview-dialog.js b/src/main/webapp/scripts/project/expression-preview-dialog.js
index 65ea302d5..5df517f1d 100644
--- a/src/main/webapp/scripts/project/expression-preview-dialog.js
+++ b/src/main/webapp/scripts/project/expression-preview-dialog.js
@@ -81,33 +81,70 @@ ExpressionPreviewDialog.prototype._renderHelpTab = function() {
 ExpressionPreviewDialog.prototype._renderHelp = function(data) {
     var elmt = this._elmts.helpTabBody.empty();
     
+    $('<h3></h3>').text("Variables").appendTo(elmt);
+    var varTable = $('<table width="100%" cellspacing="5"></table>').appendTo(elmt)[0];
+    var vars = [
+        {   name: "cell",
+            description: "The current cell. It has a few fields: 'value' and 'recon'."
+        },
+        {   name: "value",
+            description: "The current cell's value. This is a shortcut for 'cell.value'."
+        },
+        {   name: "row",
+            description: "The current row. It has 4 fields: 'flagged', 'starred', 'index', and 'cells'."
+        },
+        {   name: "cells",
+            description: "The cells of the current row. This is a shortcut for 'row.cells'. " +
+                "A particular cell can be retrieved with 'cells.<column name>' if the <column name> is a single word, " +
+                "or with 'cells[\"<column name>\"] otherwise."
+        },
+        {   name: "rowIndex",
+            description: "The current row's index. This is a shortcut for 'row.index'."
+        }
+    ];
+    for (var i = 0; i < vars.length; i++) {
+        var variable = vars[i];
+        var tr = varTable.insertRow(varTable.rows.length);
+        $(tr.insertCell(0)).addClass("expression-preview-doc-item-title").text(variable.name);
+        $(tr.insertCell(1)).addClass("expression-preview-doc-item-desc").text(variable.description);
+    }
+    
     var renderEntry = function(table, name, entry) {
         var tr0 = table.insertRow(table.rows.length);
         var tr1 = table.insertRow(table.rows.length);
         var tr2 = table.insertRow(table.rows.length);
         
-        $(tr0.insertCell(0)).text(name);
-        $(tr0.insertCell(1)).text("(" + entry.params + ")");
+        $(tr0.insertCell(0)).addClass("expression-preview-doc-item-title").text(name);
+        $(tr0.insertCell(1)).addClass("expression-preview-doc-item-params").text("(" + entry.params + ")");
         
         $(tr1.insertCell(0));
-        $(tr1.insertCell(1)).text("returns: " + entry.returns);
+        $(tr1.insertCell(1)).addClass("expression-preview-doc-item-returns").text("returns: " + entry.returns);
         
         $(tr2.insertCell(0));
-        $(tr2.insertCell(1)).text(entry.description);
+        $(tr2.insertCell(1)).addClass("expression-preview-doc-item-desc").text(entry.description);
+    };
+    var renderEntries = function(table, map) {
+        var names = [];
+        for (var n in map) {
+            if (map.hasOwnProperty(n)) {
+                names.push(n);
+            }
+        }
+        names.sort();
+        
+        for (var i = 0; i < names.length; i++) {
+            var name = names[i];
+            renderEntry(table, name, map[name]);
+        }
     };
     
     $('<h3></h3>').text("Functions").appendTo(elmt);
-    var functionTable = $('<table width="100%"></table>').appendTo(elmt)[0];
+    var functionTable = $('<table width="100%" cellspacing="5"></table>').appendTo(elmt)[0];
+    renderEntries(functionTable, data.functions);
     
     $('<h3></h3>').text("Controls").appendTo(elmt);
-    var controlTable = $('<table width="100%"></table>').appendTo(elmt)[0];
-    
-    for (var n in data.functions) {
-        renderEntry(functionTable, n, data.functions[n]);
-    }
-    for (var n in data.controls) {
-        renderEntry(controlTable, n, data.controls[n]);
-    }
+    var controlTable = $('<table width="100%" cellspacing="5"></table>').appendTo(elmt)[0];
+    renderEntries(controlTable, data.controls);
 };
 
 ExpressionPreviewDialog.prototype._scheduleUpdate = function() {
diff --git a/src/main/webapp/styles/expression-preview-dialog.css b/src/main/webapp/styles/expression-preview-dialog.css
index 77dbd70bc..3a4e2faa7 100644
--- a/src/main/webapp/styles/expression-preview-dialog.css
+++ b/src/main/webapp/styles/expression-preview-dialog.css
@@ -2,11 +2,6 @@
     padding: 7px;
 }
 
-.expression-preview-help-container {
-    height: 300px;
-    padding: 5px;
-    overflow: auto;
-}
 .expression-preview-container {
     height: 300px;
     padding: 5px;
@@ -26,4 +21,30 @@ td.expression-preview-heading {
 
 .expression-preview-empty {
     color: #aaa;
+}
+
+.expression-preview-help-container {
+    height: 300px;
+    padding: 5px;
+    overflow: auto;
+}
+
+.expression-preview-help-container h3 {
+    background: white;
+    padding: 3px 10px;
+}
+
+.expression-preview-doc-item-title {
+    font-weight: bold;
+    text-align: right;
+}
+
+.expression-preview-doc-item-params {
+}
+
+.expression-preview-doc-item-returns {
+}
+
+.expression-preview-doc-item-desc {
+    color: #666;
 }
\ No newline at end of file