diff --git a/source/common.h b/source/common.h
index 6f40f7d..5aba29a 100644
--- a/source/common.h
+++ b/source/common.h
@@ -120,6 +120,15 @@ static inline int enumMax() {
 	return QMetaEnum::fromType<T>().keyCount();
 }
 
+template<typename T>
+static inline T orThrow(Option<T> opt, Error err) {
+	if(opt) {
+		return *opt;
+	} else {
+		throw err;
+	}
+}
+
 static inline QDebug operator<<(QDebug debug, std::string const &t) {
 	debug << QString::fromStdString(t);
 	return debug;
diff --git a/source/quam/archive.cc b/source/quam/archive.cc
index 000c4b9..6a5b3e9 100644
--- a/source/quam/archive.cc
+++ b/source/quam/archive.cc
@@ -18,14 +18,42 @@ namespace Arc {
 		return None;
 	}
 
-	Dir readArchive(std::istream &st) {
-		switch(auto v = getArchiveType(st);
-		       v.has_value() ? *v : throw FileFormatError("not an archive")) {
+	Dir Dir::readArchive(std::istream &st, ArcType type) {
+		switch(type) {
 			case ArcType::Pack: return readPack(st);
 			case ArcType::Wad2: return readWad2(st);
 		}
 	}
 
+	ArcInfo::ArcInfo(ArcType arcType) noexcept :
+		type{arcType}
+	{
+		switch(type) {
+			case ArcType::Pack:
+				pathMaxChars  = 56;
+				validatorType = PackValidator::staticMetaObject;
+				break;
+			case ArcType::Wad2:
+				pathMaxChars  = 16;
+				validatorType = Wad2Validator::staticMetaObject;
+				break;
+		}
+	}
+
+	Arc::Arc(std::istream &st, QObject *parent) :
+		QObject{parent},
+		info{ArcInfo(orThrow(getArchiveType(st),
+		             FileFormatError("not an archive")))},
+		root{Dir::readArchive(st, info.type)},
+		validator{qobject_cast<QValidator *>(info.validatorType
+		                                         .newInstance(Q_ARG(QObject *,
+		                                                            this)))}
+	{
+	}
+
+	Arc::~Arc() {
+	}
+
 	Node *Dir::findNode(std::string const &name) {
 		auto it = std::find_if(begin(), end(), [&name](Node &node) {
 			return node.name == name;
@@ -143,17 +171,25 @@ namespace Arc {
 		return m_dir;
 	}
 
-	void Model::setDir(Dir *dir) {
-		if(dir != m_dir) {
+	void Model::setDir(Dir *to) {
+		auto from = m_dir;
+		if(to != from) {
 			emit layoutAboutToBeChanged();
 			for(int row = 0, rows = rowCount(); row < rows; row++) {
 				for(int col = 0, cols = columnCount(); col < cols; col++) {
 					changePersistentIndex(index(row, col), QModelIndex{});
 				}
 			}
-			m_dir = dir;
+			m_dir = to;
 			emit layoutChanged();
-			emit dirChanged(dir);
+			emit dirChanged(from, to);
+		}
+	}
+
+	void Model::setDirToIndex(QModelIndex const &ind) {
+		auto node = static_cast<Node *>(ind.data(Qt::UserRole).value<void *>());
+		if(auto dir = std::get_if<Dir>(node)) {
+			setDir(dir);
 		}
 	}
 }
diff --git a/source/quam/archive.h b/source/quam/archive.h
index 2ad12b6..de67f4c 100644
--- a/source/quam/archive.h
+++ b/source/quam/archive.h
@@ -4,14 +4,13 @@
 
 #include <QAbstractItemModel>
 #include <QByteArray>
+#include <QMetaObject>
 #include <QObject>
+#include <QValidator>
 
 namespace Arc {
 	Q_NAMESPACE
 
-	struct Node;
-	struct Dir;
-
 	enum class Column {
 		Size,
 		Type,
@@ -36,14 +35,14 @@ namespace Arc {
 	};
 	Q_ENUM_NS(ArcType)
 
-	Option<ArcType> getArchiveType(std::istream &st) noexcept;
-
-	Dir readArchive(std::istream &st);
+	struct Node;
 
 	struct Dir : public std::vector<Node> {
 		using std::vector<Node>::vector;
 
 		Node *findNode(std::string const &name);
+
+		static Dir readArchive(std::istream &st, ArcType type);
 	};
 
 	struct File : public QByteArray {
@@ -89,13 +88,36 @@ namespace Arc {
 
 	public slots:
 		void setDir(Dir *dir);
+		void setDirToIndex(QModelIndex const &ind);
 
 	signals:
-		void dirChanged(Dir *dir);
+		void dirChanged(Dir *from, Dir *to);
 
 	private:
 		Dir *m_dir;
 	};
+
+	struct ArcInfo {
+		ArcInfo(ArcType arcType) noexcept;
+
+		ArcType     type;
+		std::size_t pathMaxChars;
+		QMetaObject validatorType;
+	};
+
+	class Arc : QObject {
+		Q_OBJECT
+
+	public:
+		explicit Arc(std::istream &st, QObject *parent = nullptr);
+		~Arc();
+
+		ArcInfo     info;
+		Dir         root;
+		QValidator *validator;
+	};
+
+	Option<ArcType> getArchiveType(std::istream &st) noexcept;
 }
 Q_DECLARE_METATYPE(Arc::Dir)
 Q_DECLARE_METATYPE(Arc::File)
diff --git a/source/quam/main.cc b/source/quam/main.cc
index aabad62..dca3194 100644
--- a/source/quam/main.cc
+++ b/source/quam/main.cc
@@ -43,9 +43,7 @@ static int modeText(int argc, char *argv[]) {
 	auto fileName = par.value(fileNameOpt).toStdString();
 
 	auto st  = openReadBin(fileName);
-	auto arc = Arc::readArchive(st);
-
-	qDebug() << arc;
+	qDebug() << Arc::Arc(st).root;
 
 	return 0;
 }
diff --git a/source/quam/main_window.cc b/source/quam/main_window.cc
index f5831d9..78076be 100644
--- a/source/quam/main_window.cc
+++ b/source/quam/main_window.cc
@@ -34,9 +34,8 @@ void MainWindow::fileOpen() {
 
 	if(!fileName.isEmpty()) {
 		try {
-			auto st  = openReadBin(fileName.toStdString());
-			auto arc = Arc::readArchive(st);
-			new Project{std::move(arc), m_errors, mdiArea};
+			auto st = openReadBin(fileName.toStdString());
+			new Project{st, m_errors, mdiArea};
 		} catch(std::exception const &exc) {
 			m_errors->showMessage(tr(exc.what()));
 		}
diff --git a/source/quam/pack.cc b/source/quam/pack.cc
index 6ccff84..1cbc08c 100644
--- a/source/quam/pack.cc
+++ b/source/quam/pack.cc
@@ -93,4 +93,13 @@ Arc::Dir readPack(std::istream &st) {
 	return root;
 }
 
+PackValidator::PackValidator(QObject *parent) :
+	QValidator{parent}
+{
+}
+
+QValidator::State PackValidator::validate(QString &input, int &pos) const {
+	return QValidator::Acceptable;
+}
+
 // EOF
diff --git a/source/quam/pack.h b/source/quam/pack.h
index 63b26e6..bd0b402 100644
--- a/source/quam/pack.h
+++ b/source/quam/pack.h
@@ -4,6 +4,17 @@
 
 #include "quam/archive.h"
 
+#include <QValidator>
+
+class PackValidator : public QValidator {
+	Q_OBJECT
+
+public:
+	Q_INVOKABLE explicit PackValidator(QObject *parent);
+
+	QValidator::State validate(QString &input, int &pos) const override;
+};
+
 Arc::Dir readPack(std::istream &st);
 
 // EOF
diff --git a/source/quam/project.cc b/source/quam/project.cc
index c13805c..01d7131 100644
--- a/source/quam/project.cc
+++ b/source/quam/project.cc
@@ -5,15 +5,17 @@
 #include <QMdiArea>
 #include <QSortFilterProxyModel>
 
-Project::Project(Arc::Dir &&arc, QErrorMessage *errors, QMdiArea *parent) :
+Project::Project(std::istream &st, QErrorMessage *errors, QMdiArea *parent) :
 	QMdiSubWindow{parent},
 	Ui::Project{},
-	m_arc{std::move(arc)},
+	m_arc{new Arc::Arc{st, this}},
+	m_root{&m_arc->root},
+	m_lastDir{nullptr},
 	m_errors{errors},
 	m_model{new Arc::Model{this}},
 	m_sorter{new QSortFilterProxyModel{this}}
 {
-	auto widget = new QWidget(this);
+	auto widget = new QWidget{this};
 	setupUi(widget);
 	setWidget(widget);
 	setAttribute(Qt::WA_DeleteOnClose);
@@ -22,26 +24,19 @@ Project::Project(Arc::Dir &&arc, QErrorMessage *errors, QMdiArea *parent) :
 	connect(m_model, &Arc::Model::dirChanged,
 	        this,    &Project::dirChanged);
 	connect(tableView, &QAbstractItemView::doubleClicked,
-	        this,      &Project::viewDoubleClicked);
+	        m_model,   &Arc::Model::setDirToIndex);
 
 	m_sorter->setSourceModel(m_model);
 	tableView->setModel(m_sorter);
-	m_model->setDir(&m_arc);
+	m_model->setDir(m_root);
 }
 
 Project::~Project() {
 }
 
-void Project::dirChanged(Arc::Dir *) {
+void Project::dirChanged(Arc::Dir *from, Arc::Dir *to) {
+	m_lastDir = from;
 	tableView->resizeColumnsToContents();
 }
 
-void Project::viewDoubleClicked(QModelIndex const &index) {
-	auto node = static_cast<Arc::Node *>(index.data(Qt::UserRole)
-	                                          .value<void *>());
-	if(auto dir = std::get_if<Arc::Dir>(node)) {
-		m_model->setDir(dir);
-	}
-}
-
 // EOF
diff --git a/source/quam/project.h b/source/quam/project.h
index 73a1826..ece5a7a 100644
--- a/source/quam/project.h
+++ b/source/quam/project.h
@@ -17,15 +17,15 @@ class Project : public QMdiSubWindow, private Ui::Project {
 	Q_OBJECT
 
 public:
-	explicit Project(Arc::Dir &&arc, QErrorMessage *errors, QMdiArea *parent);
+	explicit Project(std::istream &st, QErrorMessage *errors, QMdiArea *parent);
 	virtual ~Project();
 
 private slots:
-	void dirChanged(Arc::Dir *dir);
-	void viewDoubleClicked(QModelIndex const &index);
+	void dirChanged(Arc::Dir *from, Arc::Dir *to);
 
 private:
-	Arc::Dir               m_arc;
+	Arc::Arc              *m_arc;
+	Arc::Dir              *m_root, *m_lastDir;
 	QErrorMessage         *m_errors;
 	Arc::Model            *m_model;
 	QSortFilterProxyModel *m_sorter;
diff --git a/source/quam/project.ui b/source/quam/project.ui
index c7b429d..e646aff 100644
--- a/source/quam/project.ui
+++ b/source/quam/project.ui
@@ -19,43 +19,66 @@
      <property name="orientation">
       <enum>Qt::Horizontal</enum>
      </property>
-     <widget class="QTableView" name="tableView">
-      <property name="verticalScrollBarPolicy">
-       <enum>Qt::ScrollBarAlwaysOn</enum>
-      </property>
-      <property name="horizontalScrollBarPolicy">
-       <enum>Qt::ScrollBarAlwaysOff</enum>
-      </property>
-      <property name="autoScroll">
-       <bool>false</bool>
-      </property>
-      <property name="tabKeyNavigation">
-       <bool>true</bool>
-      </property>
-      <property name="alternatingRowColors">
-       <bool>true</bool>
-      </property>
-      <property name="selectionMode">
-       <enum>QAbstractItemView::SingleSelection</enum>
-      </property>
-      <property name="selectionBehavior">
-       <enum>QAbstractItemView::SelectRows</enum>
-      </property>
-      <property name="showGrid">
-       <bool>false</bool>
-      </property>
-      <property name="sortingEnabled">
-       <bool>true</bool>
-      </property>
-      <attribute name="horizontalHeaderVisible">
-       <bool>true</bool>
-      </attribute>
-      <attribute name="horizontalHeaderStretchLastSection">
-       <bool>true</bool>
-      </attribute>
-      <attribute name="verticalHeaderVisible">
-       <bool>false</bool>
-      </attribute>
+     <widget class="QWidget" name="">
+      <layout class="QVBoxLayout" name="verticalLayout_3">
+       <item>
+        <layout class="QHBoxLayout" name="horizontalLayout_2">
+         <item>
+          <widget class="QLineEdit" name="dirName"/>
+         </item>
+         <item>
+          <widget class="QPushButton" name="buttonUp">
+           <property name="icon">
+            <iconset theme="go-up"/>
+           </property>
+           <property name="flat">
+            <bool>true</bool>
+           </property>
+          </widget>
+         </item>
+        </layout>
+       </item>
+       <item>
+        <widget class="QTableView" name="tableView">
+         <property name="verticalScrollBarPolicy">
+          <enum>Qt::ScrollBarAlwaysOn</enum>
+         </property>
+         <property name="horizontalScrollBarPolicy">
+          <enum>Qt::ScrollBarAlwaysOff</enum>
+         </property>
+         <property name="autoScroll">
+          <bool>false</bool>
+         </property>
+         <property name="tabKeyNavigation">
+          <bool>true</bool>
+         </property>
+         <property name="alternatingRowColors">
+          <bool>true</bool>
+         </property>
+         <property name="selectionMode">
+          <enum>QAbstractItemView::SingleSelection</enum>
+         </property>
+         <property name="selectionBehavior">
+          <enum>QAbstractItemView::SelectRows</enum>
+         </property>
+         <property name="showGrid">
+          <bool>false</bool>
+         </property>
+         <property name="sortingEnabled">
+          <bool>true</bool>
+         </property>
+         <attribute name="horizontalHeaderVisible">
+          <bool>true</bool>
+         </attribute>
+         <attribute name="horizontalHeaderStretchLastSection">
+          <bool>true</bool>
+         </attribute>
+         <attribute name="verticalHeaderVisible">
+          <bool>false</bool>
+         </attribute>
+        </widget>
+       </item>
+      </layout>
      </widget>
      <widget class="QPlainTextEdit" name="textEdit"/>
     </widget>
diff --git a/source/quam/wad2.cc b/source/quam/wad2.cc
index 996bb2b..e2dec57 100644
--- a/source/quam/wad2.cc
+++ b/source/quam/wad2.cc
@@ -88,4 +88,13 @@ Arc::Dir readWad2(std::istream &st) {
 	return root;
 }
 
+Wad2Validator::Wad2Validator(QObject *parent) :
+	QValidator{parent}
+{
+}
+
+QValidator::State Wad2Validator::validate(QString &input, int &pos) const {
+	return QValidator::Acceptable;
+}
+
 // EOF
diff --git a/source/quam/wad2.h b/source/quam/wad2.h
index 01d0acd..6a35f7b 100644
--- a/source/quam/wad2.h
+++ b/source/quam/wad2.h
@@ -4,6 +4,17 @@
 
 #include "quam/archive.h"
 
+#include <QValidator>
+
+class Wad2Validator : public QValidator {
+	Q_OBJECT
+
+public:
+	Q_INVOKABLE explicit Wad2Validator(QObject *parent);
+
+	QValidator::State validate(QString &input, int &pos) const override;
+};
+
 Arc::Dir readWad2(std::istream &st);
 
 // EOF