diff --git a/src/app.cpp b/src/app.cpp
index 596ece9..15cc3d9 100644
--- a/src/app.cpp
+++ b/src/app.cpp
@@ -495,7 +495,7 @@ bool App::update_ui_observer(Node *n)
             n->handle_on_screen(false, true);
             n->m_on_screen = true;
         }
-        glm::ivec4 c = glm::vec4(box.x, (height / zoom - box.y - box.w), box.z, box.w) * zoom;
+        glm::ivec4 c = glm::vec4(box.x - 1, (height / zoom - box.y - box.w - 1), box.z + 2, box.w + 2) * zoom;
         glScissor(floorf(c.x + off_x), floorf(c.y + off_y), ceilf(c.z), ceilf(c.w));
         n->draw();
         return true;
@@ -532,7 +532,7 @@ void App::draw(float dt)
         glBindFramebuffer(GL_FRAMEBUFFER, 0);
 #endif
         glViewport(off_x, off_y, (GLsizei)width, (GLsizei)height);
-        //glEnable(GL_SCISSOR_TEST);
+        glEnable(GL_SCISSOR_TEST);
         for (int i = 0; i < layout[main_id]->m_children.size(); i++)
             layout[main_id]->m_children[i]->watch(observer);
         //msgbox->watch(observer);
diff --git a/src/app.h b/src/app.h
index c8bd09a..c06dd70 100644
--- a/src/app.h
+++ b/src/app.h
@@ -284,8 +284,8 @@ public:
 
     // don't capture a reference to this ptr as the object may be destroyed
     // by the time the task is executed
-    template<typename T, typename R = void>
-    std::future<R> render_task_async(T task, bool unique = false)
+    template<typename T>
+    std::future<void> render_task_async(T task, bool unique = false)
     {
         AppTask pt(task);
         auto f = pt.get_future();
@@ -308,8 +308,8 @@ public:
         return f;
     }
 
-    template<typename T, typename R = void>
-    R render_task(T task)
+    template<typename T>
+    void render_task(T task)
     {
         AppTask pt(task);
         auto f = pt.get_future();
@@ -325,7 +325,8 @@ public:
             }
             render_cv.notify_all();
         }
-        return render_running ? f.get() : R();
+        if (render_running)
+            f.get();
     }
 
     void render_sync()
@@ -354,8 +355,8 @@ public:
 
     // don't capture a reference to this ptr as the object may be destroyed
     // by the time the task is executed
-    template<typename T, typename R = void>
-    std::future<R> ui_task_async(T task, bool unique = false)
+    template<typename T>
+    std::future<void> ui_task_async(T task, bool unique = false)
     {
         AppTask pt(task);
         auto f = pt.get_future();
@@ -378,8 +379,8 @@ public:
         return f;
     }
 
-    template<typename T, typename R = void>
-    R ui_task(T task)
+    template<typename T>
+    void ui_task(T task)
     {
         AppTask pt(task);
         auto f = pt.get_future();
@@ -395,7 +396,9 @@ public:
             }
             ui_cv.notify_all();
         }
-        return ui_running ? f.get(), redraw = true : R();
+        if (ui_running)
+            f.get();
+        redraw = true;
     }
 
     void ui_sync()
diff --git a/src/canvas.cpp b/src/canvas.cpp
index 54435bc..a85a0b2 100644
--- a/src/canvas.cpp
+++ b/src/canvas.cpp
@@ -1968,7 +1968,7 @@ void Canvas::export_cube_faces_thread(std::string file_name)
         pb->increment();
 
 #ifdef __IOS__
-        save_image_library(name);
+        save_image_library(path);
 #endif
 #ifdef __OBJC__
         [files addObject : [NSString stringWithUTF8String:path.c_str()] ];
@@ -1980,10 +1980,10 @@ void Canvas::export_cube_faces_thread(std::string file_name)
 #ifdef __OBJC__
     static char name[128];
     sprintf(name, "%s.zip", App::I->work_path.c_str());
-    auto zip_path = [NSString stringWithUTF8String : name];
+    auto zip_path = [NSString stringWithUTF8String:name];
     //[SSZipArchive createZipFileAtPath:zip_path withFilesAtPaths:files];
-    for (NSString* f : files)
-        [[NSFileManager defaultManager] removeItemAtPath:f error:nil];
+    //for (NSString* f : files)
+    //    [[NSFileManager defaultManager] removeItemAtPath:f error:nil];
 #endif
 }
 
diff --git a/src/node.cpp b/src/node.cpp
index e96a6ca..c14c8d9 100644
--- a/src/node.cpp
+++ b/src/node.cpp
@@ -58,13 +58,13 @@ void Node::watch(std::function<bool(Node*)> observer)
 
 void Node::destroy()
 {
-    auto children_copy = m_children;
-    for (auto c : children_copy)
-        c->destroy();
-    mouse_release();
-    key_release();
-    remove_from_parent();
-    app_redraw();
+    App::I->ui_task([&]
+    {
+        mouse_release();
+        key_release();
+        remove_all_children();
+        remove_from_parent();
+    });
 }
 
 Node* Node::root()
@@ -79,11 +79,11 @@ kEventResult Node::on_event(Event* e)
 {
     kEventResult ret = kEventResult::Available;
     
-    if (current_mouse_capture && current_mouse_capture != this)
+    if (current_mouse_capture && current_mouse_capture.get() != this)
     {
         if (e->m_cat == kEventCategory::MouseEvent && 
             child_mouse_focus != current_mouse_capture &&
-            is_child(current_mouse_capture))
+            is_child(current_mouse_capture.get()))
         {
             MouseEvent* me = static_cast<MouseEvent*>(e);
             if (child_mouse_focus)
@@ -112,7 +112,7 @@ kEventResult Node::on_event(Event* e)
     }
 
     skip_children |= (e->m_cat == kEventCategory::MouseEvent || e->m_cat == kEventCategory::GestureEvent) &&
-        (m_mouse_captured) && (root()->current_mouse_capture == this) && m_capture_children; // <-- THIS IS WRONG "!m_capture_children" is correct, but it breaks everything if changed
+        (m_mouse_captured) && (root()->current_mouse_capture.get() == this) && m_capture_children; // <-- THIS IS WRONG "!m_capture_children" is correct, but it breaks everything if changed
     
     if (!m_display || glm::any(glm::lessThanEqual(zw(m_clip), { 0, 0 })))
         return kEventResult::Available;
@@ -131,7 +131,7 @@ kEventResult Node::on_event(Event* e)
                 }
                 else
                 {
-                    if (e->m_cat == kEventCategory::MouseEvent && child_mouse_focus != it->get())
+                    if (e->m_cat == kEventCategory::MouseEvent && child_mouse_focus.get() != it->get())
                     {
                         MouseEvent* me = static_cast<MouseEvent*>(e);
                         if (child_mouse_focus)
@@ -144,7 +144,7 @@ kEventResult Node::on_event(Event* e)
                         MouseEvent e2 = *me;
                         e2.m_type = kEventType::MouseFocus;
                         (*it)->handle_event(&e2);
-                        child_mouse_focus = it->get();
+                        child_mouse_focus = *it;
                         child_mouse_focus->m_mouse_focus = true;
                     }
                     ret = kEventResult::Consumed;
@@ -398,7 +398,7 @@ void Node::remove_child(Node* n)
             YGNodeRemoveChild(y_node, n->y_node);
             on_child_removed(n);
             m_children.erase(i);
-            if (child_mouse_focus == n)
+            if (child_mouse_focus.get() == n)
                 child_mouse_focus = nullptr;
         });
     }
@@ -539,7 +539,8 @@ void Node::mouse_capture()
     auto& s = root()->m_capture_stack;
 
     // already owner of capture
-    if (c == this || std::find(s.begin(), s.end(), this) != s.end())
+    if (c.get() == this || std::find_if(s.begin(), s.end(),
+        [this](const auto& a) { return a.get() == this; }) != s.end())
         return;
 
     if (c)
@@ -567,7 +568,7 @@ void Node::mouse_capture()
     }
     
     // make current
-    c = this;
+    c = shared_from_this();
     m_mouse_captured = true;
 }
 
@@ -579,8 +580,9 @@ void Node::mouse_release()
     auto& c = root()->current_mouse_capture;
     auto& s = root()->m_capture_stack;
 
-    s.erase(std::remove(s.begin(), s.end(), this), s.end());
-    if (c == this)
+    s.erase(std::remove_if(s.begin(), s.end(),
+        [this](const auto& a) { return a.get() == this; }), s.end());
+    if (c.get() == this)
     {
         if (s.empty())
         {
@@ -601,7 +603,7 @@ void Node::key_capture()
     if (!m_parent)
         return;
 
-    root()->current_key_capture = this;
+    root()->current_key_capture = shared_from_this();
     m_key_captured = true;
 }
 
diff --git a/src/node.h b/src/node.h
index 720a086..652a601 100644
--- a/src/node.h
+++ b/src/node.h
@@ -103,9 +103,9 @@ public:
     uint16_t m_nodeID;
     std::string m_nodeID_s;
     std::vector<std::shared_ptr<Node>> m_children;
-    Node* current_mouse_capture = nullptr;
-    Node* current_key_capture = nullptr;
-    Node* child_mouse_focus = nullptr;
+    std::shared_ptr<Node> current_mouse_capture = nullptr;
+    std::shared_ptr<Node> current_key_capture = nullptr;
+    std::shared_ptr<Node> child_mouse_focus = nullptr;
     bool m_mouse_captured = false;
     bool m_key_captured = false;
 
@@ -116,7 +116,7 @@ public:
     bool m_flood_events = false;
     bool m_force_mouse_capture = false;
     bool m_capture_children = true; // wether to capture children events when xx_capture() is used
-    std::vector<Node*> m_capture_stack;
+    std::vector<std::shared_ptr<Node>> m_capture_stack;
 
     bool m_mouse_ignore = true;
     float m_zoom = 1.f;
diff --git a/src/node_canvas.cpp b/src/node_canvas.cpp
index b24bb6a..a21d322 100644
--- a/src/node_canvas.cpp
+++ b/src/node_canvas.cpp
@@ -63,6 +63,14 @@ void NodeCanvas::clear_context()
 
 void NodeCanvas::draw()
 {
+    // sanity checks
+    float zoom = root()->m_zoom;
+    if (zoom == 0.f)
+        zoom = 1.f;
+    auto box = m_clip * zoom;
+    if (box.z == 0 || box.w == 0)
+        return;
+
     GLint vp[4];
     GLfloat cc[4];
     glGetIntegerv(GL_VIEWPORT, vp);
@@ -73,8 +81,6 @@ void NodeCanvas::draw()
 
     glDisable(GL_SCISSOR_TEST);
 
-    float zoom = root()->m_zoom;
-    auto box = m_clip * zoom;
     glm::ivec4 c = (glm::ivec4)glm::vec4(box.x, (int)(vp[3] - box.y - box.w), box.z, box.w);
 
     //m_canvas->m_cam_rot = m_pan * 0.003f;
diff --git a/src/node_combobox.cpp b/src/node_combobox.cpp
index 2240f27..3c742ea 100644
--- a/src/node_combobox.cpp
+++ b/src/node_combobox.cpp
@@ -53,10 +53,10 @@ void NodeComboBox::loaded()
                     m_current_index = index;
                     m_selected_child_index = popup->get_child_index(target);
                     m_text->set_text(m_items[index].c_str());
-                    popup->mouse_release();
-                    popup->destroy();
                     if (on_select)
                         on_select(btn, index);
+                    popup->mouse_release();
+                    popup->destroy();
                 };
             }
         }