diff --git a/src/data/field.cpp b/src/data/field.cpp
index 3f7c688b..685bf079 100644
--- a/src/data/field.cpp
+++ b/src/data/field.cpp
@@ -99,6 +99,14 @@ template <> StyleP read_new<Style>(Reader&) {
 	throw InternalError(_("IndexMap contains nullptr StyleP the application should have crashed already"));
 }
 
+bool Style::update(Context& ctx) {
+	return left   .update(ctx)
+	     | top    .update(ctx)
+	     | width  .update(ctx)
+	     | height .update(ctx)
+	     | visible.update(ctx);
+}
+
 void Style::initDependencies(Context& ctx, const Dependency& dep) const {
 	left   .initDependencies(ctx,dep);
 	top    .initDependencies(ctx,dep);
diff --git a/src/data/field.hpp b/src/data/field.hpp
index 098f4b1d..7848fb9b 100644
--- a/src/data/field.hpp
+++ b/src/data/field.hpp
@@ -12,6 +12,7 @@
 #include <util/prec.hpp>
 #include <util/reflect.hpp>
 #include <util/alignment.hpp>
+#include <util/age.hpp>
 #include <script/scriptable.hpp>
 #include <script/dependency.hpp>
 
@@ -96,6 +97,8 @@ class Style {
 	/** thisP is a smart pointer to this */
 	virtual ValueEditorP makeEditor(DataEditor& parent, const StyleP& thisP) = 0;
 	
+	/// Update scripted values of this style, return true if anything has changed
+	virtual bool update(Context&);
 	/// Add the given dependency to the dependet_scripts list for the variables this style depends on
 	virtual void initDependencies(Context&, const Dependency&) const;
 	
@@ -116,10 +119,13 @@ class Value {
 	inline Value(const FieldP& field) : fieldP(field) {}
 	virtual ~Value();
 	
-	const FieldP       fieldP;			///< Field this value is for, should have the right type!
-		
+	const FieldP fieldP;				///< Field this value is for, should have the right type!
+	Age          last_script_update;	///< When where the scripts last updated? (by calling update)
+	
 	/// Convert this value to a string for use in tables
 	virtual String toString() const = 0;
+	/// Apply scripts to this value, return true if the value has changed
+	virtual bool update(Context&) { last_script_update.update(); return false; }
 	
   private:
 	DECLARE_REFLECTION_VIRTUAL();
diff --git a/src/data/field/choice.cpp b/src/data/field/choice.cpp
index 1a6ebbd6..c401f8ee 100644
--- a/src/data/field/choice.cpp
+++ b/src/data/field/choice.cpp
@@ -9,6 +9,8 @@
 #include <data/field/choice.hpp>
 
 DECLARE_TYPEOF_COLLECTION(ChoiceField::ChoiceP);
+typedef map<String,ScriptableImage> map_String_ScriptableImage;
+DECLARE_TYPEOF(map_String_ScriptableImage);
 
 // ----------------------------------------------------------------------------- : ChoiceField
 
@@ -23,6 +25,12 @@ String ChoiceField::typeName() const {
 	return _("choice");
 }
 
+void ChoiceField::initDependencies(Context& ctx, const Dependency& dep) const {
+	Field        ::initDependencies(ctx, dep);
+	script        .initDependencies(ctx, dep);
+	default_script.initDependencies(ctx, dep);
+}
+
 IMPLEMENT_REFLECTION(ChoiceField) {
 	REFLECT_BASE(Field);
 	REFLECT_N("choices", choices->choices);
@@ -156,6 +164,24 @@ ChoiceStyle::ChoiceStyle(const ChoiceFieldP& field)
 	, colors_card_list(false)
 {}
 
+// TODO
+/*
+void ChoiceStyle::invalidate() {
+	// rebuild choice images
+}
+}
+*/
+bool ChoiceStyle::update(Context& ctx) {
+	// Don't update the choice images, leave that to invalidate()
+	return Style::update(ctx);
+}
+void ChoiceStyle::initDependencies(Context& ctx, const Dependency& dep) const {
+	Style::initDependencies(ctx, dep);
+	FOR_EACH_CONST(ci, choice_images) {
+		ci.second.initDependencies(ctx, dep);
+	}
+}
+
 IMPLEMENT_REFLECTION_ENUM(ChoicePopupStyle) {
 	VALUE_N("dropdown",	POPUP_DROPDOWN);
 	VALUE_N("menu",		POPUP_MENU);
@@ -190,6 +216,11 @@ IMPLEMENT_REFLECTION(ChoiceStyle) {
 String ChoiceValue::toString() const {
 	return value();
 }
+bool ChoiceValue::update(Context& ctx) {
+	Value::update(ctx);
+	return field().default_script.invokeOnDefault(ctx, value)
+	     | field().        script.invokeOn(ctx, value);
+}
 
 IMPLEMENT_REFLECTION_NAMELESS(ChoiceValue) {
 	REFLECT_NAMELESS(value);
diff --git a/src/data/field/choice.hpp b/src/data/field/choice.hpp
index 107d47c3..89885f46 100644
--- a/src/data/field/choice.hpp
+++ b/src/data/field/choice.hpp
@@ -36,7 +36,9 @@ class ChoiceField : public Field {
 	OptionalScript default_script;	///< Script that generates the default value
 	String initial;					///< Initial choice of a new value, or ""
 	String default_name;			///< Name of "default" value
-		
+	
+	virtual void initDependencies(Context&, const Dependency&) const;
+	
   private:
 	DECLARE_REFLECTION();
 };
@@ -123,6 +125,9 @@ class ChoiceStyle : public Style {
 	ImageCombine				combine;		///< Combining mode for drawing the images
 	Alignment					alignment;		///< Alignment of images
 	
+	virtual bool update(Context&);
+	virtual void initDependencies(Context&, const Dependency&) const;
+	
   private:
 	DECLARE_REFLECTION();
 };
@@ -138,6 +143,7 @@ class ChoiceValue : public Value {
 	Defaultable<String> value;	/// The name of the selected choice
 	
 	virtual String toString() const;
+	virtual bool update(Context&);
 	
   private:
 	DECLARE_REFLECTION();
diff --git a/src/data/set.cpp b/src/data/set.cpp
index 7d7fb614..1e9caf59 100644
--- a/src/data/set.cpp
+++ b/src/data/set.cpp
@@ -46,6 +46,11 @@ Context& Set::getContext(const Card& card) {
 	return script_manager->getContext(card.stylesheet ? card.stylesheet : stylesheet);
 }
 
+StyleSheetP Set::stylesheetFor(const CardP& card) {
+	if (card && card->stylesheet) return card->stylesheet;
+	else                          return stylesheet;
+}
+
 String Set::typeName() const { return _("set"); }
 
 // fix values for versions < 0.2.7
diff --git a/src/data/set.hpp b/src/data/set.hpp
index 2ba8596f..179a84aa 100644
--- a/src/data/set.hpp
+++ b/src/data/set.hpp
@@ -54,11 +54,13 @@ class Set : public Packaged {
 	/// A context for performing scripts
 	/** Should only be used from the main thread! */
 	Context& getContext();
-	
 	/// A context for performing scripts on a particular card
 	/** Should only be used from the main thread! */
 	Context& getContext(const Card& card);
 	
+	/// Stylesheet to use for a particular card
+	StyleSheetP stylesheetFor(const CardP& card);
+	
   protected:
 	virtual String typeName() const;
 	virtual void validate(Version);
diff --git a/src/render/symbol/filter.cpp b/src/render/symbol/filter.cpp
index 77f39250..9b54fd4e 100644
--- a/src/render/symbol/filter.cpp
+++ b/src/render/symbol/filter.cpp
@@ -97,6 +97,9 @@ IMPLEMENT_REFLECTION(GradientSymbolFilter) {
 
 // ----------------------------------------------------------------------------- : LinearGradientSymbolFilter
 
+// TODO: move to some general util header
+inline double sqr(double x) { return x * x; }
+
 String LinearGradientSymbolFilter::fillType() const { return _("linear gradient"); }
 
 LinearGradientSymbolFilter::LinearGradientSymbolFilter()
@@ -105,12 +108,14 @@ LinearGradientSymbolFilter::LinearGradientSymbolFilter()
 {}
 
 AColor LinearGradientSymbolFilter::color(double x, double y, SymbolSet point) const {
+	len = sqr(end_x - center_x) + sqr(end_y - center_y);
+	if (len == 0) len = 1; // prevent div by 0
 	return GradientSymbolFilter::color(x,y,point,this);
 }
 
 double LinearGradientSymbolFilter::t(double x, double y) const {
-	//return abs( int(x - center_x) * dirX + int(y - centerY) * dirY)  * scale;
-	return 0; // todo
+	double t= abs( (x - center_x) * (end_x - center_x) + (y - center_y) * (end_y - center_y)) / len;
+	return min(1.,max(0.,t));
 }
 
 IMPLEMENT_REFLECTION(LinearGradientSymbolFilter) {
@@ -127,9 +132,6 @@ AColor RadialGradientSymbolFilter::color(double x, double y, SymbolSet point) co
 	return GradientSymbolFilter::color(x,y,point,this);
 }
 
-// TODO: move to some general util header
-inline double sqr(double x) { return x * x; }
-
 double RadialGradientSymbolFilter::t(double x, double y) const {
 	return sqrt( (sqr(x - 0.5) + sqr(y - 0.5)) * 2); 
 }
diff --git a/src/render/symbol/filter.hpp b/src/render/symbol/filter.hpp
index 2079bd72..26b47398 100644
--- a/src/render/symbol/filter.hpp
+++ b/src/render/symbol/filter.hpp
@@ -94,6 +94,7 @@ class LinearGradientSymbolFilter : public GradientSymbolFilter {
   private:
 	double center_x, center_y;
 	double end_x,    end_y;
+	mutable double len;
 	DECLARE_REFLECTION();
 };
 
diff --git a/src/script/dependency.cpp b/src/script/dependency.cpp
index 2ec35759..78c172cc 100644
--- a/src/script/dependency.cpp
+++ b/src/script/dependency.cpp
@@ -25,9 +25,11 @@ class DependencyDummy : public ScriptIterator {
 	virtual ScriptType type() const { return SCRIPT_DUMMY; }
 	virtual String typeName() const { return _("dummy"); }
 	virtual ScriptValueP next() { return ScriptValueP(); }
+	virtual ScriptValueP eval(Context&)           const { return dependency_dummy; } // dummy() == dummy
+	virtual ScriptValueP getMember(const String&) const { return dependency_dummy; } // dummy.* = dummy
 };
 
-ScriptValueP dependencyDummy(new DependencyDummy);
+ScriptValueP dependency_dummy(new DependencyDummy);
 
 ScriptValueP unified(const ScriptValueP& a, const ScriptValueP& b);
 
@@ -220,7 +222,7 @@ ScriptValueP Context::dependencies(const Dependency& dep, const Script& script)
 					assert(dynamic_pointer_cast<ScriptIterator>(it)); // top of stack must be an iterator
 					ScriptValueP val = static_pointer_cast<ScriptIterator>(it)->next();
 					if (val) {
-						it = dependencyDummy; // invalidate iterator, so we loop only once
+						it = dependency_dummy; // invalidate iterator, so we loop only once
 						stack.push_back(val);
 					} else {
 						stack.erase(stack.end() - 2); // remove iterator
@@ -259,7 +261,9 @@ ScriptValueP Context::dependencies(const Dependency& dep, const Script& script)
 				// Get a variable (almost as normal)
 				case I_GET_VAR: {
 					ScriptValueP value = variables[i.data].value;
-					if (!value) value = new_intrusive1<ScriptMissingVariable>(variable_to_string(i.data)); // no errors here
+					if (!value) {
+						value = new_intrusive1<ScriptMissingVariable>(variable_to_string(i.data)); // no errors here
+					}
 					stack.push_back(value);
 					break;
 				}
@@ -277,7 +281,7 @@ ScriptValueP Context::dependencies(const Dependency& dep, const Script& script)
 							a = a->makeIterator(); // as normal
 							break;
 						default:
-							a = dependencyDummy;
+							a = dependency_dummy;
 					}
 					break;
 				}
@@ -298,7 +302,7 @@ ScriptValueP Context::dependencies(const Dependency& dep, const Script& script)
 							unify(a, b); // may be function composition
 							break;
 						default:
-							a = dependencyDummy;
+							a = dependency_dummy;
 					}
 					break;
 				}
@@ -307,7 +311,7 @@ ScriptValueP Context::dependencies(const Dependency& dep, const Script& script)
 					ScriptValueP  c = stack.back(); stack.pop_back();
 					ScriptValueP  b = stack.back(); stack.pop_back();
 					ScriptValueP& a = stack.back();
-					a = dependencyDummy;
+					a = dependency_dummy;
 					break;
 				}
 			}
diff --git a/src/script/image.hpp b/src/script/image.hpp
index 5ed11b42..4a0276f3 100644
--- a/src/script/image.hpp
+++ b/src/script/image.hpp
@@ -11,9 +11,9 @@
 
 #include <util/prec.hpp>
 #include <util/age.hpp>
+#include <util/dynamic_arg.hpp>
 #include <script/scriptable.hpp>
 #include <gfx/gfx.hpp>
-#include <util/dynamic_arg.hpp>
 
 class Package;
 DECLARE_INTRUSIVE_POINTER_TYPE(ScriptImage);
@@ -64,6 +64,10 @@ class ScriptableImage {
 	/// Is the cached image up to date?
 	bool upToDate(Context& ctx, Age age) const;
 	
+	inline void initDependencies(Context& ctx, const Dependency& dep) const {
+		script.initDependencies(ctx, dep);
+	}
+	
   private:
 	OptionalScript script;		///< The script, not really optional
 	ScriptImageP   cache;		///< The cached image
diff --git a/src/script/script_manager.cpp b/src/script/script_manager.cpp
index 4f5e2a66..ddb30d8b 100644
--- a/src/script/script_manager.cpp
+++ b/src/script/script_manager.cpp
@@ -10,14 +10,19 @@
 #include <data/set.hpp>
 #include <data/stylesheet.hpp>
 #include <data/game.hpp>
+#include <data/card.hpp>
 #include <data/field.hpp>
 #include <util/error.hpp>
 
 typedef map<const StyleSheet*,Context*> Contexts;
 typedef IndexMap<FieldP,StyleP> IndexMap_FieldP_StyleP;
+typedef IndexMap<FieldP,ValueP> IndexMap_FieldP_ValueP;
 DECLARE_TYPEOF(Contexts);
+DECLARE_TYPEOF_COLLECTION(CardP);
 DECLARE_TYPEOF_COLLECTION(FieldP);
+DECLARE_TYPEOF_COLLECTION(Dependency);
 DECLARE_TYPEOF_NO_REV(IndexMap_FieldP_StyleP);
+DECLARE_TYPEOF_NO_REV(IndexMap_FieldP_ValueP);
 
 // initialize functions, from functions.cpp
 void init_script_functions(Context& ctx);
@@ -58,9 +63,9 @@ Context& ScriptManager::getContext(const StyleSheetP& stylesheet) {
 		ctx->setVariable(_("card"),       set.cards.empty() ? script_nil : toScript(set.cards.front())); // dummy value
 		//ctx->setVariable(_("styling"), toScript(set->extraStyleData(style)));
 		try {
-			// perform init scripts
-			set.game  ->init_script.invoke(*ctx);
-			stylesheet->init_script.invoke(*ctx);
+			// perform init scripts, don't use a scope, variables stay bound in the context
+			set.game  ->init_script.invoke(*ctx, false);
+			stylesheet->init_script.invoke(*ctx, false);
 			// find script dependencies
 			initDependencies(*ctx, *set.game);
 			initDependencies(*ctx, *stylesheet);
@@ -97,12 +102,140 @@ void ScriptManager::initDependencies(Context& ctx, StyleSheet& stylesheet) {
 	}
 }
 
-// ----------------------------------------------------------------------------- : ScriptManager : dependency handling
+// ----------------------------------------------------------------------------- : ScriptManager : updating
 
 void ScriptManager::onAction(const Action& action, bool undone) {
 	// TODO
+//	TYPE_CASE(action, ValueAction) {
+//	}
+//	TYPE_CASE(action, CardListAction) {
+//	}
+}
+
+void ScriptManager::updateStyles(const CardP& card) {
+//	lastUpdatedCard = card;
+	StyleSheetP stylesheet = set.stylesheetFor(card);
+	Context& ctx = getContext(stylesheet);
+	// update all styles
+	FOR_EACH(s, stylesheet->card_style) {
+		if (s->update(ctx)) {
+			// style has changed, tell listeners
+//			ScriptStyleEvent change(s.get());
+//			set->actions.tellListeners(change);
+		}
+	}
+}
+
+void ScriptManager::updateValue(Value& value, const CardP& card) {
+	Age starting_age; // the start of the update process
+	deque<ToUpdate> to_update;
+	// execute script for initial changed value
+	value.update(getContext(set.stylesheetFor(card)));
+	// update dependent scripts
+	alsoUpdate(to_update, value.fieldP->dependent_scripts, card);
+	updateRecursive(to_update, starting_age);
 }
 
 void ScriptManager::updateAll() {
-	// TODO
+	// update set data
+	Context& ctx = getContext(set.stylesheet);
+	FOR_EACH(v, set.data) {
+		v->update(ctx);
+	}
+	// update card data of all cards
+	FOR_EACH(card, set.cards) {
+		Context& ctx = getContext(set.stylesheetFor(card));
+		FOR_EACH(v, card->data) {
+			v->update(ctx);
+		}
+	}
+	// update things that depend on the card list
+	updateAllDependend(set.game->dependent_scripts_cards);
+}
+
+void ScriptManager::updateAllDependend(const vector<Dependency>& dependent_scripts) {
+	deque<ToUpdate> to_update;
+	Age starting_age;
+	alsoUpdate(to_update, dependent_scripts, CardP());
+	updateRecursive(to_update, starting_age);
+}
+
+void ScriptManager::updateRecursive(deque<ToUpdate>& to_update, Age starting_age) {
+//	set->order_cache.clear(); // clear caches before evaluating a round of scripts
+	while (!to_update.empty()) {
+		updateToUpdate(to_update.front(), to_update, starting_age);
+		to_update.pop_front();
+	}
+}
+
+void ScriptManager::updateToUpdate(const ToUpdate& u, deque<ToUpdate>& to_update, Age starting_age) {
+	Age age = u.value->last_script_update;
+	if (starting_age < age)  return; // this value was already updated
+	Context& ctx = getContext(set.stylesheetFor(u.card));
+	if (u.value->update(ctx)) {
+		// changed, send event
+//		ScriptValueEvent change(&*u.card, u.value);
+//		set.actions.tellListeners(change);
+		// u.value has changed, also update values with a dependency on u.value
+		alsoUpdate(to_update, u.value->fieldP->dependent_scripts, u.card);
+	}
+}
+
+void ScriptManager::alsoUpdate(deque<ToUpdate>& to_update, const vector<Dependency>& deps, const CardP& card) {
+	FOR_EACH_CONST(d, deps) {
+		switch (d.type) {
+			case DEP_SET_FIELD: {
+				break;
+			} case DEP_CARD_FIELD: {
+				break;
+			} case DEP_CARDS_FIELD: {
+				break;
+			} case DEP_STYLE: {
+				break;
+			} case DEP_CARD_COPY_DEP: {
+				break;
+			} case DEP_SET_COPY_DEP: {
+				break;
+			} default:
+				assert(false);
+		}
+		/*
+		if (d.type == DependendScript.setField) {
+			// from set data
+			ValueP value = set->data.at(ds.index);
+			toUpdate.push_back(ToUpdate(&*value));
+		} else if (ds.type == DependendScript.cardField) {
+			// from the same card's data
+			assert(card);
+			ValueP value = card->data.at(ds.index);
+			toUpdate.push_back(ToUpdate(&*value, card));
+		} else if (ds.type == DependendScript.cardsField) {
+			// something invalidates a card value for all cards, so all cards need updating
+			FOR_EACH(card, set)->cards {
+				ValueP value = card->data.at(ds.index);
+				toUpdate.push_back(ToUpdate(&*value, card));
+			}
+		} else if (ds.type >= DependendScript.choiceImage) {
+			// a generated image has become invalid, there is not much we can do
+			// because the index is not exact enough, it only gives the field
+			// TODO : Indicate what style
+			//CardStyleP style = set->styleOf(card) // WRONG?
+			CardStyle* style = CardStyle.getByIndex(ds.type - DependendScript.choiceImage);
+			StyleP s = style->cardStyle.at(ds.index);
+			s->invalidate();
+			// something changed, send event
+			ScriptStyleEvent change(&*s);
+			set->actions.tellListeners(change);
+		} else if (ds.type == DependendScript.cardCopyDep) {
+			// propagate dependencies from another field
+			FieldP f = game->cardFields#(ds.index);
+			alsoUpdate(toUpdate, f->dependendScripts, card);
+		} else if (ds.type == DependendScript.setCopyDep) {
+			// propagate dependencies from another field
+			FieldP f = game->setFields#(ds.index);
+			alsoUpdate(toUpdate, f->dependendScripts, card);
+		} else {
+			assert(false); // only setField, cardField and cardsField should be possible
+		}*/
+	}
 }
\ No newline at end of file
diff --git a/src/script/script_manager.hpp b/src/script/script_manager.hpp
index 1d4d19e2..0a25b121 100644
--- a/src/script/script_manager.hpp
+++ b/src/script/script_manager.hpp
@@ -11,8 +11,10 @@
 
 #include <util/prec.hpp>
 #include <util/action_stack.hpp>
+#include <util/age.hpp>
 #include <script/context.hpp>
 #include <script/dependency.hpp>
+#include <queue>
 
 class Set;
 class Value;
@@ -37,10 +39,13 @@ class ScriptManager : public ActionListener {
   public:
 	ScriptManager(Set& set);
 	~ScriptManager();
-		
+	
 	/// Get a context to use for the set, for a given stylesheet
 	Context& getContext(const StyleSheetP& s);
 	
+	// Update all styles for a particular card
+	void updateStyles(const CardP& card);
+	
   private:
 	Set&                            set;		///< Set for which we are managing scripts
 	map<const StyleSheet*,Context*> contexts;	///< Context for evaluating scripts that use a given stylesheet
@@ -48,18 +53,29 @@ class ScriptManager : public ActionListener {
 	void initDependencies(Context&, Game&);
 	void initDependencies(Context&, StyleSheet&);
 	
-	// Update all styles for a particular card
-	void updateStyles(const CardP& card);
 	/// Updates scripts, starting at some value
 	/** if the value changes any dependend values are updated as well */
-	void updateValue(Value* value, const CardP& card);
+	void updateValue(Value& value, const CardP& card);
 	/// Update all fields of all cards
 	/** Update all set info fields
 	 *  Doesn't update styles
 	 */
 	void updateAll();
 	// Update all values with a specific dependency
-	void updateAllDependend(const vector<Dependency>& dependendScripts);
+	void updateAllDependend(const vector<Dependency>& dependent_scripts);
+	
+	// Something that needs to be updated
+	struct ToUpdate {
+		Value* value;  // value to update
+		CardP  card;   // card the value is in, or 0 if it is not a card field
+	};
+	/// Update all things in to_update, and things that depent on them, etc.
+	/** Only update things that are older than starting_age. */
+	void updateRecursive(deque<ToUpdate>& to_update, Age starting_age);
+	/// Update a value given by a ToUpdate object, and add things depending on it to to_update
+	void updateToUpdate(const ToUpdate& u, deque<ToUpdate>& to_update, Age starting_age);
+	/// Schedule all things in deps to be updated by adding them to to_update
+	void alsoUpdate(deque<ToUpdate>& to_update, const vector<Dependency>& deps, const CardP& card);
 	
   protected:
 	/// Respond to actions by updating scripts
diff --git a/src/script/scriptable.cpp b/src/script/scriptable.cpp
index 050bd7fd..dddaa229 100644
--- a/src/script/scriptable.cpp
+++ b/src/script/scriptable.cpp
@@ -24,9 +24,9 @@ void store(const ScriptValueP& val, Defaultable<String>& var) { var.assign(*val)
 
 OptionalScript::~OptionalScript() {}
 
-ScriptValueP OptionalScript::invoke(Context& ctx) const {
+ScriptValueP OptionalScript::invoke(Context& ctx, bool open_scope) const {
 	if (script) {
-		return ctx.eval(*script);
+		return ctx.eval(*script, open_scope);
 	} else {
 		return script_nil;
 	}
diff --git a/src/script/scriptable.hpp b/src/script/scriptable.hpp
index a60d4608..907ea8b0 100644
--- a/src/script/scriptable.hpp
+++ b/src/script/scriptable.hpp
@@ -13,10 +13,10 @@
 #include <util/reflect.hpp>
 #include <util/defaultable.hpp>
 #include <script/script.hpp>
+#include <script/context.hpp>
 #include <script/parser.hpp>
 
 DECLARE_INTRUSIVE_POINTER_TYPE(Script);
-class Context;
 
 // ----------------------------------------------------------------------------- : Store
 
@@ -37,7 +37,7 @@ class OptionalScript {
 	inline operator bool() const { return !!script; }
 	
 	/// Invoke the script, return the result, or script_nil if there is no script
-	ScriptValueP invoke(Context& ctx) const;
+	ScriptValueP invoke(Context& ctx, bool open_scope = true) const;
 	
 	/// Invoke the script on a value
 	/** Assigns the result to value if it has changed.
@@ -47,7 +47,8 @@ class OptionalScript {
 	bool invokeOn(Context& ctx, T& value) const {
 		if (script) {
 			T new_value;
-			store(new_value, script->invoke(ctx));
+			ctx.setVariable(_("value"), toScript(value));
+			store(ctx.eval(*script), new_value);
 			if (value != new_value) {
 				value = new_value;
 				return true;
@@ -55,6 +56,16 @@ class OptionalScript {
 		}
 		return false;
 	}
+	/// Invoke the script on a value if it is in the default state
+	template <typename T>
+	bool invokeOnDefault(Context& ctx, Defaultable<T>& value) const {
+		if (value.isDefault() && invokeOn(ctx, value)) {
+			value.setDefault(); // restore defaultness
+			return true;
+		} else {
+			return false;
+		}
+	}
 	
 	/// Initialize things this script depends on by adding dep to their list of dependent scripts
 	void initDependencies(Context&, const Dependency& dep) const;
@@ -68,6 +79,9 @@ class OptionalScript {
 	template <typename T> friend class Scriptable;
 };
 
+template <typename T>
+inline ScriptValueP toScript(const Defaultable<T>& v) { return toScript(v.get()); }
+
 // ----------------------------------------------------------------------------- : Scriptable
 
 /// A script that defines a calculation to find a value
diff --git a/src/script/value.cpp b/src/script/value.cpp
index df51a441..729330c6 100644
--- a/src/script/value.cpp
+++ b/src/script/value.cpp
@@ -13,20 +13,18 @@
 // ----------------------------------------------------------------------------- : ScriptValue
 // Base cases
 
-ScriptValue::operator String() const { return _("[[") + typeName() + _("]]"); }
-ScriptValue::operator int()    const { throw ScriptError(_("Can't convert from ")+typeName()+_(" to integer number")); }
-ScriptValue::operator double() const { throw ScriptError(_("Can't convert from ")+typeName()+_(" to real number"   )); }
-ScriptValue::operator Color()  const { throw ScriptError(_("Can't convert from ")+typeName()+_(" to color"         )); }
-ScriptValueP ScriptValue::eval(Context&) const
-                                     { throw ScriptError(_("Can't convert from ")+typeName()+_(" to function"      )); }
-ScriptValueP ScriptValue::getMember(const String& name) const
-                                     { throw ScriptError(typeName() + _(" has no member '") + name + _("'")); }
-ScriptValueP ScriptValue::next()               { throw InternalError(_("Can't convert from ")+typeName()+_(" to iterator")); }
-ScriptValueP ScriptValue::makeIterator() const { throw ScriptError(  _("Can't convert from ")+typeName()+_(" to collection")); }
-int          ScriptValue::itemCount()    const { throw ScriptError(  _("Can't convert from ")+typeName()+_(" to collection")); }
+ScriptValue::operator String()                          const { return _("[[") + typeName() + _("]]"); }
+ScriptValue::operator int()                             const { throw ScriptError(  _("Can't convert from ")+typeName()+_(" to integer number")); }
+ScriptValue::operator double()                          const { throw ScriptError(  _("Can't convert from ")+typeName()+_(" to real number"   )); }
+ScriptValue::operator Color()                           const { throw ScriptError(  _("Can't convert from ")+typeName()+_(" to color"         )); }
+ScriptValueP ScriptValue::eval(Context&)                const { throw ScriptError(  _("Can't convert from ")+typeName()+_(" to function"      )); }
+ScriptValueP ScriptValue::getMember(const String& name) const { throw ScriptError(typeName() + _(" has no member '") + name + _("'")); }
+ScriptValueP ScriptValue::next()                              { throw InternalError(_("Can't convert from ")+typeName()+_(" to iterator")); }
+ScriptValueP ScriptValue::makeIterator()                const { throw ScriptError(  _("Can't convert from ")+typeName()+_(" to collection")); }
+int          ScriptValue::itemCount()                   const { throw ScriptError(  _("Can't convert from ")+typeName()+_(" to collection")); }
 
 void ScriptValue::signalDependent(Context&, const Dependency&, const String& name) {}
-ScriptValueP ScriptValue::dependencies(   Context&, const Dependency&) const { return script_nil; }
+ScriptValueP ScriptValue::dependencies(Context&, const Dependency&) const { return dependency_dummy; }
 
 
 // ----------------------------------------------------------------------------- : Iterators
diff --git a/src/script/value.hpp b/src/script/value.hpp
index 1d44fe18..f50b07e2 100644
--- a/src/script/value.hpp
+++ b/src/script/value.hpp
@@ -114,7 +114,7 @@ class ScriptValue {
 extern ScriptValueP script_nil;   ///< The preallocated nil value
 extern ScriptValueP script_true;  ///< The preallocated true value
 extern ScriptValueP script_false; ///< The preallocated false value
-
+extern ScriptValueP dependency_dummy; ///< Dummy value used during dependency analysis
 
 // ----------------------------------------------------------------------------- : Iterators
 
diff --git a/src/util/defaultable.hpp b/src/util/defaultable.hpp
index 944c007f..60c26677 100644
--- a/src/util/defaultable.hpp
+++ b/src/util/defaultable.hpp
@@ -35,6 +35,12 @@ class Defaultable {
 	
 	/// Is this value in the default state?
 	inline bool isDefault() const { return is_default; }
+	/// Set the defaultness to true
+	inline void setDefault() { is_default = true; }
+	
+	/// Compare the values, ignore defaultness
+	/** used by scriptable to check for changes */
+	inline bool operator != (const Defaultable& that) const { return value != that.value; }
 	
   private:
 	/// Is this value in the default state?
@@ -46,7 +52,6 @@ class Defaultable {
 	friend class Writer;
 };
 
-
 // we need some custom io, because the behaviour is different for each of Reader/Writer/GetMember
 
 template <typename T>