diff --git a/include/scripting.h b/include/scripting.h
index e98cdccf..15332c51 100644
--- a/include/scripting.h
+++ b/include/scripting.h
@@ -48,7 +48,9 @@ public:
     static void stop();
     static void populateGlobalObject(MainWindow *mainWindow);
     static QJSEngine *getEngine();
+    static QString getCurrentScriptHash();
     static void invokeAction(int actionIndex);
+    static void setTimeout(QJSValue callback, int milliseconds);
 
     static void cb_ProjectOpened(QString projectPath);
     static void cb_ProjectClosed(QString projectPath);
@@ -82,32 +84,33 @@ private:
     MainWindow *mainWindow;
     QJSEngine *engine;
 
-    class Script {
-        public:
-            Script() {};
+    class Script
+    {
+    public:
+        Script() {};
 
-            QString filepath() const { return m_filepath; }
-            QString fileName() const {
-                QFileInfo fileInfo(m_filepath);
-                return fileInfo.fileName();
+        QString filepath() const { return m_filepath; }
+        QString fileName() const {
+            QFileInfo fileInfo(m_filepath);
+            return fileInfo.fileName();
+        }
+        void setFilepath(const QString &filepath) { m_filepath = filepath; }
+
+        QJSValue module() const { return m_module; }
+        void setModule(const QJSValue &module) { m_module = module; }
+
+        QString hash() {
+            if (m_hash.isEmpty()) {
+                // We won't need to check whether most scripts are trusted,
+                // so only calculate the hash when it's first requested.
+                m_hash = Util::getFileHash(m_filepath);
             }
-            void setFilepath(const QString &filepath) { m_filepath = filepath; }
-
-            QJSValue module() const { return m_module; }
-            void setModule(const QJSValue &module) { m_module = module; }
-
-            QString hash() {
-                if (m_hash.isEmpty()) {
-                    // We won't need to check whether most scripts are trusted,
-                    // so only calculate the hash when it's first requested.
-                    m_hash = Util::getFileHash(m_filepath);
-                }
-                return m_hash;
-            }
-        private:
-            QString m_filepath;
-            QJSValue m_module;
-            QString m_hash;
+            return m_hash;
+        }
+    private:
+        QString m_filepath;
+        QJSValue m_module;
+        QString m_hash;
     };
     QList<QSharedPointer<Script>> scripts;
 
@@ -119,14 +122,14 @@ private:
     // track of multiple scripts executing at once.
     QStack<QSharedPointer<Script>> scriptExecutionStack;
 
+    QSet<QTimer *> activeTimers;
     QMap<QString, const QImage*> imageCache;
     ScriptUtility *scriptUtility;
 
     void loadScript(const QString &filepath);
     void invokeCallback(CallbackType type, const QJSValueList &args);
-    void invokeCallback(QSharedPointer<const Script> script, CallbackType type, const QJSValueList &args);
-    bool invokeAction(QSharedPointer<const Script> script, const QString &functionName);
     QSharedPointer<Script> getActiveScript() const;
+    QJSValue call(QSharedPointer<Script> script, QJSValue func, const QJSValueList &args = QJSValueList());
     bool askForTrust(QSharedPointer<Script> script, const QString &reason);
 };
 
diff --git a/include/scriptutility.h b/include/scriptutility.h
index 23d42d99..87c63c9a 100644
--- a/include/scriptutility.h
+++ b/include/scriptutility.h
@@ -75,13 +75,11 @@ public:
     static bool validateMetatileLayerOrder(const QList<int> &order);
 
 private:
-    void callTimeoutFunction(QJSValue callback);
     void runMessageBox(QString text, QString informativeText, QString detailedText, QMessageBox::Icon icon);
     QString detectProjectPath(const QString &path) const;
 
     MainWindow *window;
     QList<QAction *> registeredActions;
-    QSet<QTimer *> activeTimers;
     QHash<int, QString> actionMap;
 };
 
diff --git a/include/ui/graphicsview.h b/include/ui/graphicsview.h
index 31859ce9..8d80e5ad 100644
--- a/include/ui/graphicsview.h
+++ b/include/ui/graphicsview.h
@@ -125,7 +125,14 @@ signals:
     void pressedDelete();
 
 protected:
-    virtual void keyPressEvent(QKeyEvent *event) override;
+    virtual void keyPressEvent(QKeyEvent *event) override {
+        if (event->key() == Qt::Key_Delete || event->key() == Qt::Key_Backspace) {
+            emit pressedDelete();
+            event->accept();
+        } else {
+            QGraphicsView::keyPressEvent(event);
+        }
+    }
 };
 
 #endif // GRAPHICSVIEW_H
diff --git a/include/ui/mapview.h b/include/ui/mapview.h
index 5f65b20b..a822b958 100644
--- a/include/ui/mapview.h
+++ b/include/ui/mapview.h
@@ -23,8 +23,8 @@ public:
 
     Editor *editor;
 
-    Overlay * getOverlay(int layer);
-    void clearOverlayMap();
+    void clearOverlay();
+    void renderOverlay(QPainter*);
 
     // Overlay scripting API
 #ifdef QT_QML_LIB
@@ -80,6 +80,7 @@ public:
     Q_INVOKABLE void addTileImage(int x, int y, int tileId, bool xflip, bool yflip, int paletteId, bool setTransparency = false, int layer = 0);
     Q_INVOKABLE void addTileImage(int x, int y, QJSValue tileObj, bool setTransparency = false, int layer = 0);
     Q_INVOKABLE void addMetatileImage(int x, int y, int metatileId, bool setTransparency = false, int layer = 0);
+    Q_INVOKABLE void setRenderPriority(int priority);
 #endif // QT_QML_LIB
 
 protected:
@@ -87,10 +88,34 @@ protected:
     virtual void keyPressEvent(QKeyEvent*) override;
     virtual void moveEvent(QMoveEvent *event) override;
 private:
-    QMap<int, Overlay*> overlayMap;
+#ifdef QT_QML_LIB
+    // Maps a layer number to the overlay items.
+    // We specifically use a QMap because we guarantee a sorted
+    // order for the layers so that users can predict rendering.
+    typedef QMap<int, Overlay*> OverlayLayers;
 
+    // Maps a script's file hash to a priority value.
+    // This priority value is the order in which all layers
+    // belonging to that script will be rendered relative to
+    // the layers belonging to other scripts.
+    // These are normally unique and automatically assigned,
+    // but users may set this value manually to render scripts
+    // in an explicit order relative to one another, or even
+    // to have multiple scripts share layers.
+    // This is a QMap vs a QHash solely for performance,
+    // given most users will have relatively few scripts.
+    QMap<QString, int> hashToPriority;
+
+    // Maps a render priority provided by 'hashToPriority'
+    // to the corresponding overlay layers.
+    // A QMap is used once again to guarantee render order.
+    QMap<int, OverlayLayers> overlayMap;
+
+    OverlayLayers* getCurrentScriptLayers();
+    Overlay * getOverlay(int layer);
     void updateScene();
     void addTileImage(int x, int y, const Tile &tile, bool setTransparency, int layer = 0);
+#endif
 };
 
 #endif // GRAPHICSVIEW_H
diff --git a/include/ui/overlay.h b/include/ui/overlay.h
index 9be73ec8..165a1737 100644
--- a/include/ui/overlay.h
+++ b/include/ui/overlay.h
@@ -125,17 +125,6 @@ private:
     QRectF *clippingRect;
 };
 
-#else
-
-class Overlay
-{
-public:
-    Overlay() {}
-    ~Overlay() {}
-
-    void renderItems(QPainter *) {}
-};
-
 #endif // QT_QML_LIB
 
 #endif // OVERLAY_H
diff --git a/porymap.pro b/porymap.pro
index 88f4b698..27c11ba5 100644
--- a/porymap.pro
+++ b/porymap.pro
@@ -108,7 +108,7 @@ SOURCES += src/core/advancemapparser.cpp \
     src/ui/maplistmodels.cpp \
     src/ui/maplisttoolbar.cpp \
     src/ui/message.cpp \
-    src/ui/graphicsview.cpp \
+    src/ui/mapview.cpp \
     src/ui/imageproviders.cpp \
     src/ui/layoutpixmapitem.cpp \
     src/ui/prefabcreationdialog.cpp \
diff --git a/src/mainwindow.cpp b/src/mainwindow.cpp
index b0f3848c..6a6a93ec 100644
--- a/src/mainwindow.cpp
+++ b/src/mainwindow.cpp
@@ -3240,7 +3240,7 @@ bool MainWindow::askToFixRegionMapEditor() {
 
 void MainWindow::clearOverlay() {
     if (ui->graphicsView_Map)
-        ui->graphicsView_Map->clearOverlayMap();
+        ui->graphicsView_Map->clearOverlay();
 }
 
 bool MainWindow::closeSupplementaryWindows() {
diff --git a/src/scriptapi/apioverlay.cpp b/src/scriptapi/apioverlay.cpp
index e2ca888f..b09e0d9b 100644
--- a/src/scriptapi/apioverlay.cpp
+++ b/src/scriptapi/apioverlay.cpp
@@ -4,6 +4,39 @@
 #include "imageproviders.h"
 #include "editor.h"
 
+void MapView::setRenderPriority(int priority) {
+    const QString hash = Scripting::getCurrentScriptHash();
+    if (!hash.isEmpty()) this->hashToPriority[hash] = priority;
+}
+
+MapView::OverlayLayers* MapView::getCurrentScriptLayers() {
+    int priority = 1;
+    const QString hash = Scripting::getCurrentScriptHash();
+    auto it = this->hashToPriority.find(hash);
+    if (it == this->hashToPriority.end()) {
+        // This script does not have a priority, which means
+        // the user has not assigned it one and we haven't
+        // retrieved layers for it before.
+        // Assign it a new unique priority, starting from 1.
+        QList<int> renderIds = this->hashToPriority.values();
+        while (renderIds.contains(priority)) priority++;
+        this->hashToPriority[hash] = priority;
+    } else {
+        priority = *it;
+    }
+    return &this->overlayMap[priority];
+}
+
+Overlay* MapView::getOverlay(int layer) {
+    OverlayLayers *layers = getCurrentScriptLayers();
+    Overlay *overlay = layers->value(layer, nullptr);
+    if (!overlay) {
+        overlay = new Overlay();
+        layers->insert(layer, overlay);
+    }
+    return overlay;
+}
+
 void MapView::updateScene() {
     if (this->scene()) {
         this->scene()->update();
@@ -17,7 +50,7 @@ void MapView::clear(int layer) {
 
 // Overload. No layer provided, clear all layers
 void MapView::clear() {
-    this->clearOverlayMap();
+    this->clearOverlay();
     this->updateScene();
 }
 
@@ -50,7 +83,7 @@ void MapView::setVisibility(bool visible, int layer) {
 
 // Overload. No layer provided, set visibility of all layers
 void MapView::setVisibility(bool visible) {
-    foreach (Overlay * layer, this->overlayMap)
+    for (const auto& layer : *getCurrentScriptLayers())
         layer->setHidden(!visible);
     this->updateScene();
 }
@@ -70,7 +103,7 @@ void MapView::setX(int x, int layer) {
 
 // Overload. No layer provided, set x of all layers
 void MapView::setX(int x) {
-    foreach (Overlay * layer, this->overlayMap)
+    for (const auto& layer : *getCurrentScriptLayers())
         layer->setX(x);
     this->updateScene();
 }
@@ -82,7 +115,7 @@ void MapView::setY(int y, int layer) {
 
 // Overload. No layer provided, set y of all layers
 void MapView::setY(int y) {
-    foreach (Overlay * layer, this->overlayMap)
+    for (const auto& layer : *getCurrentScriptLayers())
         layer->setY(y);
     this->updateScene();
 }
@@ -94,7 +127,7 @@ void MapView::setClippingRect(int x, int y, int width, int height, int layer) {
 
 void MapView::setClippingRect(int x, int y, int width, int height) {
     QRectF rect = QRectF(x, y, width, height);
-    foreach (Overlay * layer, this->overlayMap)
+    for (const auto& layer : *getCurrentScriptLayers())
         layer->setClippingRect(rect);
     this->updateScene();
 }
@@ -105,7 +138,7 @@ void MapView::clearClippingRect(int layer) {
 }
 
 void MapView::clearClippingRect() {
-    foreach (Overlay * layer, this->overlayMap)
+    for (const auto& layer : *getCurrentScriptLayers())
         layer->clearClippingRect();
     this->updateScene();
 }
@@ -122,7 +155,7 @@ void MapView::setPosition(int x, int y, int layer) {
 
 // Overload. No layer provided, set position of all layers
 void MapView::setPosition(int x, int y) {
-    foreach (Overlay * layer, this->overlayMap)
+    for (const auto& layer : *getCurrentScriptLayers())
         layer->setPosition(x, y);
     this->updateScene();
 }
@@ -134,7 +167,7 @@ void MapView::move(int deltaX, int deltaY, int layer) {
 
 // Overload. No layer provided, move all layers
 void MapView::move(int deltaX, int deltaY) {
-    foreach (Overlay * layer, this->overlayMap)
+    for (const auto& layer : *getCurrentScriptLayers())
         layer->move(deltaX, deltaY);
     this->updateScene();
 }
@@ -150,7 +183,7 @@ void MapView::setOpacity(int opacity, int layer) {
 
 // Overload. No layer provided, set opacity of all layers
 void MapView::setOpacity(int opacity) {
-    foreach (Overlay * layer, this->overlayMap)
+    for (const auto& layer : *getCurrentScriptLayers())
         layer->setOpacity(opacity);
     this->updateScene();
 }
@@ -170,7 +203,7 @@ void MapView::setHorizontalScale(qreal scale, int layer) {
 
 // Overload. No layer provided, set horizontal scale of all layers
 void MapView::setHorizontalScale(qreal scale) {
-    foreach (Overlay * layer, this->overlayMap)
+    for (const auto& layer : *getCurrentScriptLayers())
         layer->setHScale(scale);
     this->updateScene();
 }
@@ -182,7 +215,7 @@ void MapView::setVerticalScale(qreal scale, int layer) {
 
 // Overload. No layer provided, set vertical scale of all layers
 void MapView::setVerticalScale(qreal scale) {
-    foreach (Overlay * layer, this->overlayMap)
+    for (const auto& layer : *getCurrentScriptLayers())
         layer->setVScale(scale);
     this->updateScene();
 }
@@ -194,7 +227,7 @@ void MapView::setScale(qreal hScale, qreal vScale, int layer) {
 
 // Overload. No layer provided, set scale of all layers
 void MapView::setScale(qreal hScale, qreal vScale) {
-    foreach (Overlay * layer, this->overlayMap)
+    for (const auto& layer : *getCurrentScriptLayers())
         layer->setScale(hScale, vScale);
     this->updateScene();
 }
@@ -210,7 +243,7 @@ void MapView::setRotation(int angle, int layer) {
 
 // Overload. No layer provided, set rotation of all layers
 void MapView::setRotation(int angle) {
-    foreach (Overlay * layer, this->overlayMap)
+    for (const auto& layer : *getCurrentScriptLayers())
         layer->setRotation(angle);
     this->updateScene();
 }
@@ -222,7 +255,7 @@ void MapView::rotate(int degrees, int layer) {
 
 // Overload. No layer provided, rotate all layers
 void MapView::rotate(int degrees) {
-    foreach (Overlay * layer, this->overlayMap)
+    for (const auto& layer : *getCurrentScriptLayers())
         layer->rotate(degrees);
     this->updateScene();
 }
diff --git a/src/scriptapi/apiutility.cpp b/src/scriptapi/apiutility.cpp
index 35432b8d..eaed06bd 100644
--- a/src/scriptapi/apiutility.cpp
+++ b/src/scriptapi/apiutility.cpp
@@ -12,10 +12,6 @@ ScriptUtility::~ScriptUtility() {
             window->ui->menuTools->removeAction(action);
         }
     }
-    for (auto timer : this->activeTimers) {
-        timer->stop();
-        delete timer;
-    }
 }
 
 bool ScriptUtility::registerAction(QString functionName, QString actionName, QString shortcut) {
@@ -60,24 +56,7 @@ QString ScriptUtility::getActionFunctionName(int actionIndex) {
 }
 
 void ScriptUtility::setTimeout(QJSValue callback, int milliseconds) {
-  if (!callback.isCallable() || milliseconds < 0)
-      return;
-
-    QTimer *timer = new QTimer();
-    connect(timer, &QTimer::timeout, [=](){
-        if (this->activeTimers.remove(timer)) {
-            this->callTimeoutFunction(callback);
-            timer->deleteLater();
-        }
-    });
-
-    this->activeTimers.insert(timer);
-    timer->setSingleShot(true);
-    timer->start(milliseconds);
-}
-
-void ScriptUtility::callTimeoutFunction(QJSValue callback) {
-    Scripting::tryErrorJS(callback.call());
+    Scripting::setTimeout(callback, milliseconds);
 }
 
 void ScriptUtility::log(QString message) {
diff --git a/src/scriptapi/scripting.cpp b/src/scriptapi/scripting.cpp
index e06b707a..60b11fca 100644
--- a/src/scriptapi/scripting.cpp
+++ b/src/scriptapi/scripting.cpp
@@ -50,8 +50,12 @@ Scripting::Scripting(MainWindow *mainWindow) {
 }
 
 Scripting::~Scripting() {
-    if (mainWindow) mainWindow->clearOverlay();
     this->engine->setInterrupted(true);
+    for (auto timer : this->activeTimers) {
+        timer->stop();
+        delete timer;
+    }
+    if (mainWindow) mainWindow->clearOverlay();
     qDeleteAll(this->imageCache);
     this->scripts.clear();
     this->scriptExecutionStack.clear();
@@ -159,19 +163,21 @@ bool Scripting::tryErrorJS(QJSValue js) {
     return true;
 }
 
-void Scripting::invokeCallback(CallbackType type, const QJSValueList &args) {
-    for (const auto& script : this->scripts) {
-        this->scriptExecutionStack.push(script);
-        invokeCallback(script, type, args);
-        this->scriptExecutionStack.pop();
-    }
+QJSValue Scripting::call(QSharedPointer<Script> script, QJSValue func, const QJSValueList &args) {
+    this->scriptExecutionStack.push(script);
+    QJSValue result = func.call(args);
+    tryErrorJS(result);
+    this->scriptExecutionStack.pop();
+    return result;
 }
 
-void Scripting::invokeCallback(QSharedPointer<const Script> script, CallbackType type, const QJSValueList &args) {
-    QString functionName = callbackFunctions[type];
-    QJSValue callbackFunction = script->module().property(functionName);
-    if (tryErrorJS(callbackFunction)) return;
-    tryErrorJS(callbackFunction.call(args));
+void Scripting::invokeCallback(CallbackType type, const QJSValueList &args) {
+    for (const auto& script : this->scripts) {
+        QString functionName = callbackFunctions[type];
+        QJSValue callbackFunction = script->module().property(functionName);
+        if (tryErrorJS(callbackFunction)) return;
+        call(script, callbackFunction, args);
+    }
 }
 
 void Scripting::invokeAction(int actionIndex) {
@@ -181,9 +187,11 @@ void Scripting::invokeAction(int actionIndex) {
 
     bool foundFunction = false;
     for (const auto& script : instance->scripts) {
-        instance->scriptExecutionStack.push(script);
-        if (instance->invokeAction(script, functionName)) foundFunction = true;
-        instance->scriptExecutionStack.pop();
+        QJSValue callbackFunction = script->module().property(functionName);
+        if (callbackFunction.isUndefined() || !callbackFunction.isCallable()) continue;
+        foundFunction = true;
+        if (tryErrorJS(callbackFunction)) continue;
+        instance->call(script, callbackFunction);
     }
     if (!foundFunction) {
         logError(QString("Unknown custom script function '%1'").arg(functionName));
@@ -196,19 +204,22 @@ void Scripting::invokeAction(int actionIndex) {
     }
 }
 
-// Returns true if the script had the specified function and tried to execute it (whether successful or not),
-// returns false if the script did not have the specified function.
-// TODO: Now that we can individually identify scripts, this should never happen.
-//       We can always call the function using the script that registered this action.
-bool Scripting::invokeAction(QSharedPointer<const Script> script, const QString &functionName) {
-    QJSValue callbackFunction = script->module().property(functionName);
-    if (callbackFunction.isUndefined() || !callbackFunction.isCallable())
-        return false;
-    if (tryErrorJS(callbackFunction)) return true;
+void Scripting::setTimeout(QJSValue callback, int milliseconds) {
+  if (!instance || !callback.isCallable() || milliseconds < 0)
+      return;
 
-    QJSValue result = callbackFunction.call(QJSValueList());
-    tryErrorJS(result);
-    return true;
+    auto script = instance->getActiveScript();
+    QTimer *timer = new QTimer();
+    QObject::connect(timer, &QTimer::timeout, [=](){
+        if (instance->activeTimers.remove(timer)) {
+            instance->call(script, callback);
+            timer->deleteLater();
+        }
+    });
+
+    instance->activeTimers.insert(timer);
+    timer->setSingleShot(true);
+    timer->start(milliseconds);
 }
 
 void Scripting::cb_ProjectOpened(QString projectPath) {
@@ -460,6 +471,12 @@ bool Scripting::askForTrust(QSharedPointer<Script> script, const QString &reason
     return false;
 }
 
+QString Scripting::getCurrentScriptHash() {
+    if (!instance) return QString();
+    auto script = instance->getActiveScript();
+    return script ? script->hash() : QString();
+}
+
 QJSEngine *Scripting::getEngine() {
     return instance->engine;
 }
diff --git a/src/ui/graphicsview.cpp b/src/ui/mapview.cpp
similarity index 69%
rename from src/ui/graphicsview.cpp
rename to src/ui/mapview.cpp
index 667e0aab..214e64b2 100644
--- a/src/ui/graphicsview.cpp
+++ b/src/ui/mapview.cpp
@@ -1,4 +1,3 @@
-#include "graphicsview.h"
 #include "mapview.h"
 #include "editor.h"
 
@@ -18,12 +17,10 @@ void MapView::keyPressEvent(QKeyEvent *event) {
 }
 
 void MapView::drawForeground(QPainter *painter, const QRectF&) {
-    for (auto i = this->overlayMap.constBegin(); i != this->overlayMap.constEnd(); i++) {
-        i.value()->renderItems(painter);
-    }
-
     if (!editor) return;
 
+    renderOverlay(painter);
+
     QStyleOptionGraphicsItem option;
 
     // Draw elements of the map view that should always render on top of anything added by the user with the scripting API.
@@ -49,27 +46,21 @@ void MapView::drawForeground(QPainter *painter, const QRectF&) {
         editor->cursorMapTileRect->paint(painter, &option, this);
 }
 
-void MapView::clearOverlayMap() {
-    for (auto i = this->overlayMap.constBegin(); i != this->overlayMap.constEnd(); i++) {
-        delete i.value();
+void MapView::renderOverlay(QPainter *painter) {
+#ifdef QT_QML_LIB
+    for (auto outerIt = this->overlayMap.constBegin(); outerIt != this->overlayMap.constEnd(); outerIt++)
+    for (auto innerIt = outerIt.value().constBegin(); innerIt != outerIt.value().constEnd(); innerIt++) {
+        innerIt.value()->renderItems(painter);
+    }
+#endif
+}
+
+void MapView::clearOverlay() {
+#ifdef QT_QML_LIB
+    for (auto outerIt = this->overlayMap.constBegin(); outerIt != this->overlayMap.constEnd(); outerIt++)
+    for (auto innerIt = outerIt.value().constBegin(); innerIt != outerIt.value().constEnd(); innerIt++) {
+        delete innerIt.value();
     }
     this->overlayMap.clear();
-}
-
-Overlay * MapView::getOverlay(int layer) {
-    Overlay * overlay = this->overlayMap.value(layer, nullptr);
-    if (!overlay) {
-        overlay = new Overlay();
-        this->overlayMap.insert(layer, overlay);
-    }
-    return overlay;
-}
-
-void ConnectionsView::keyPressEvent(QKeyEvent *event) {
-    if (event->key() == Qt::Key_Delete || event->key() == Qt::Key_Backspace) {
-        emit pressedDelete();
-        event->accept();
-    } else {
-        QGraphicsView::keyPressEvent(event);
-    }
+#endif
 }