diff --git a/PanoPainter-OSX/main.cpp b/PanoPainter-OSX/main.cpp
index 04387bd..40daf05 100644
--- a/PanoPainter-OSX/main.cpp
+++ b/PanoPainter-OSX/main.cpp
@@ -214,49 +214,49 @@ static CVReturn MyDisplayLinkCallback(CVDisplayLinkRef displayLink, const CVTime
 {
     CGLLockContext([[self openGLContext] CGLContextObj]);
     auto mouseLoc = [self convertPoint:[theEvent locationInWindow] fromView:nil];
-    App::I.mouse_down(0, mouseLoc.x, App::I.height - mouseLoc.y - 1, theEvent.pressure);
+    App::I.mouse_down(0, mouseLoc.x, App::I.height - mouseLoc.y - 1, theEvent.pressure, kEventSource::Mouse);
     CGLUnlockContext([[self openGLContext] CGLContextObj]);
 }
 - (void)rightMouseDown:(NSEvent *)theEvent
 {
     CGLLockContext([[self openGLContext] CGLContextObj]);
     auto mouseLoc = [self convertPoint:[theEvent locationInWindow] fromView:nil];
-    App::I.mouse_down(1, mouseLoc.x, App::I.height - mouseLoc.y - 1, theEvent.pressure);
+    App::I.mouse_down(1, mouseLoc.x, App::I.height - mouseLoc.y - 1, theEvent.pressure, kEventSource::Mouse);
     CGLUnlockContext([[self openGLContext] CGLContextObj]);
 }
 - (void)mouseUp:(NSEvent *)theEvent
 {
     CGLLockContext([[self openGLContext] CGLContextObj]);
     auto mouseLoc = [self convertPoint:[theEvent locationInWindow] fromView:nil];
-    App::I.mouse_up(0, mouseLoc.x, App::I.height - mouseLoc.y - 1);
+    App::I.mouse_up(0, mouseLoc.x, App::I.height - mouseLoc.y - 1, kEventSource::Mouse);
     CGLUnlockContext([[self openGLContext] CGLContextObj]);
 }
 - (void)rightMouseUp:(NSEvent *)theEvent
 {
     CGLLockContext([[self openGLContext] CGLContextObj]);
     auto mouseLoc = [self convertPoint:[theEvent locationInWindow] fromView:nil];
-    App::I.mouse_up(1, mouseLoc.x, App::I.height - mouseLoc.y - 1);
+    App::I.mouse_up(1, mouseLoc.x, App::I.height - mouseLoc.y - 1, kEventSource::Mouse);
     CGLUnlockContext([[self openGLContext] CGLContextObj]);
 }
 - (void)mouseMoved:(NSEvent *)theEvent
 {
     CGLLockContext([[self openGLContext] CGLContextObj]);
     auto mouseLoc = [self convertPoint:[theEvent locationInWindow] fromView:nil];
-    App::I.mouse_move(mouseLoc.x, App::I.height - mouseLoc.y - 1, theEvent.pressure);
+    App::I.mouse_move(mouseLoc.x, App::I.height - mouseLoc.y - 1, theEvent.pressure, kEventSource::Mouse);
     CGLUnlockContext([[self openGLContext] CGLContextObj]);
 }
 -(void)mouseDragged:(NSEvent *)theEvent
 {
     CGLLockContext([[self openGLContext] CGLContextObj]);
     auto mouseLoc = [self convertPoint:[theEvent locationInWindow] fromView:nil];
-    App::I.mouse_move(mouseLoc.x, App::I.height - mouseLoc.y - 1, theEvent.pressure);
+    App::I.mouse_move(mouseLoc.x, App::I.height - mouseLoc.y - 1, theEvent.pressure, kEventSource::Mouse);
     CGLUnlockContext([[self openGLContext] CGLContextObj]);
 }
 - (void)rightMouseDragged:(NSEvent *)theEvent
 {
     CGLLockContext([[self openGLContext] CGLContextObj]);
     auto mouseLoc = [self convertPoint:[theEvent locationInWindow] fromView:nil];
-    App::I.mouse_move(mouseLoc.x, App::I.height - mouseLoc.y - 1, theEvent.pressure);
+    App::I.mouse_move(mouseLoc.x, App::I.height - mouseLoc.y - 1, theEvent.pressure, kEventSource::Mouse);
     CGLUnlockContext([[self openGLContext] CGLContextObj]);
 }
 - (void)scrollWheel:(NSEvent *)theEvent
diff --git a/PanoPainter/GameViewController.m b/PanoPainter/GameViewController.m
index fff09b9..42fe1cf 100644
--- a/PanoPainter/GameViewController.m
+++ b/PanoPainter/GameViewController.m
@@ -115,7 +115,8 @@ glm::vec2 t_pos;
     CGPoint touchLocation = [touch locationInView:self.view];
     float scale = self.view.contentScaleFactor;
     
-    App::I.mouse_down(0, touchLocation.x * scale, touchLocation.y * scale, touch.force);
+    kEventSource source = touch.type == UITouchType::UITouchTypeStylus ? kEventSource::Stylus : kEventSource::Touch;
+    App::I.mouse_down(0, touchLocation.x * scale, touchLocation.y * scale, touch.force, source);
     t_count = 1;
     t_pos = {touchLocation.x * scale, touchLocation.y * scale};
 }
@@ -162,7 +163,8 @@ glm::vec2 t_pos;
         }
         else
         {
-            App::I.mouse_move(touchLocation.x * scale, touchLocation.y * scale, force);
+            kEventSource source = touch.type == UITouchType::UITouchTypeStylus ? kEventSource::Stylus : kEventSource::Touch;
+            App::I.mouse_move(touchLocation.x * scale, touchLocation.y * scale, force, source);
         }
     }
     t_pos = {tl0.x * scale, tl0.y * scale};
@@ -172,11 +174,13 @@ glm::vec2 t_pos;
     UITouch *touch = [[event allTouches] anyObject];
     CGPoint touchLocation = [touch locationInView:self.view];
     float scale = self.view.contentScaleFactor;
-    
+
+    kEventSource source = touch.type == UITouchType::UITouchTypeStylus ? kEventSource::Stylus : kEventSource::Touch;
+
     if (t_count == 2)
         App::I.gesture_end();
     else
-        App::I.mouse_up(0, touchLocation.x * scale, touchLocation.y * scale);
+        App::I.mouse_up(0, touchLocation.x * scale, touchLocation.y * scale, source);
     t_count = 0;
     t_pos = {touchLocation.x * scale, touchLocation.y * scale};
 }
diff --git a/data/layout.xml b/data/layout.xml
index 90a2a88..301337f 100644
--- a/data/layout.xml
+++ b/data/layout.xml
@@ -454,7 +454,8 @@
         <node dir="row" justify="center" grow="1">
           <button id="btn-pen" width="50" height="100%" margin="0 0 0 0" text="Pen"/>
           <button id="btn-pick" width="50" height="100%" margin="0 0 0 0" text="Pick"/>
-          
+          <button id="btn-touchlock" width="50" height="100%" margin="0 0 0 0" text="Lock"/>
+
           <button id="btn-erase" width="60" height="100%" margin="0 0 0 5" text="Erase"/>
           
           <button id="btn-cam" width="70" height="100%" margin="0 0 0 5" text="Camera"/>
diff --git a/engine/app.cpp b/engine/app.cpp
index af7e37f..3bf898f 100644
--- a/engine/app.cpp
+++ b/engine/app.cpp
@@ -139,6 +139,8 @@ void App::update(float dt)
     CanvasModePen* mode = (CanvasModePen*)canvas->m_canvas->modes[(int)Canvas::kCanvasMode::Draw][0];
     layout[main_id]->find<NodeButton>("btn-pick")->set_color(
          mode->m_picking ? color_button_hlight : color_button_normal);
+    layout[main_id]->find<NodeButton>("btn-touchlock")->set_color(
+         canvas->m_canvas->m_touch_lock ? color_button_hlight : color_button_normal);
 
 
     auto observer = [this](Node* n)
diff --git a/engine/app.h b/engine/app.h
index 6553a8c..74fee62 100644
--- a/engine/app.h
+++ b/engine/app.h
@@ -80,9 +80,9 @@ public:
     void update_memory_usage(size_t bytes);
     void update(float dt);
     void resize(float w, float h);
-    bool mouse_down(int button, float x, float y, float pressure);
-    bool mouse_move(float x, float y, float pressure);
-    bool mouse_up(int button, float x, float y);
+    bool mouse_down(int button, float x, float y, float pressure, kEventSource source);
+    bool mouse_move(float x, float y, float pressure, kEventSource source);
+    bool mouse_up(int button, float x, float y, kEventSource source);
     bool mouse_scroll(float x, float y, float delta);
     bool mouse_cancel(int button);
     bool gesture_start(const glm::vec2& p0, const glm::vec2& p1);
diff --git a/engine/app_events.cpp b/engine/app_events.cpp
index af13567..23f35f9 100644
--- a/engine/app_events.cpp
+++ b/engine/app_events.cpp
@@ -28,35 +28,38 @@ void App::hideKeyboard()
 #endif
 }
 
-bool App::mouse_down(int button, float x, float y, float pressure)
+bool App::mouse_down(int button, float x, float y, float pressure, kEventSource source)
 {
     redraw = true;
     MouseEvent e;
     e.m_type = button ? kEventType::MouseDownR : kEventType::MouseDownL;
     e.m_pos = { x / zoom, y / zoom };
     e.m_pressure = pressure;
+    e.m_source = source;
     auto ret = layout[main_id]->on_event(&e);
     layout[main_id]->update();
     return ret == kEventResult::Consumed;
 }
-bool App::mouse_move(float x, float y, float pressure)
+bool App::mouse_move(float x, float y, float pressure, kEventSource source)
 {
     redraw = true;
     MouseEvent e;
     e.m_type = kEventType::MouseMove;
     e.m_pos = { x / zoom, y / zoom };
     e.m_pressure = pressure;
+    e.m_source = source;
     kEventResult ret = kEventResult::Available;
     if (auto* main = layout[main_id])
         ret = main->on_event(&e);
     return ret == kEventResult::Consumed;
 }
-bool App::mouse_up(int button, float x, float y)
+bool App::mouse_up(int button, float x, float y, kEventSource source)
 {
     redraw = true;
     MouseEvent e;
     e.m_type = button ? kEventType::MouseUpR : kEventType::MouseUpL;
     e.m_pos = { x / zoom, y / zoom };
+    e.m_source = source;
     auto ret = layout[main_id]->on_event(&e);
     layout[main_id]->update();
     return ret == kEventResult::Consumed;
diff --git a/engine/app_layout.cpp b/engine/app_layout.cpp
index 4904a9c..dedb284 100644
--- a/engine/app_layout.cpp
+++ b/engine/app_layout.cpp
@@ -240,6 +240,12 @@ void App::init_toolbar_draw()
             }
         };
     }
+    if (auto* button = layout[main_id]->find<NodeButton>("btn-touchlock"))
+    {
+        button->on_click = [this](Node*) {
+            canvas->m_canvas->m_touch_lock = !canvas->m_canvas->m_touch_lock;
+        };
+    }
     if (auto* button = layout[main_id]->find<NodeButton>("btn-erase"))
     {
         button->on_click = [this](Node*) {
diff --git a/engine/app_shaders.cpp b/engine/app_shaders.cpp
index db154de..73b2b04 100644
--- a/engine/app_shaders.cpp
+++ b/engine/app_shaders.cpp
@@ -228,7 +228,7 @@ void App::initShaders()
 #else
         "   mediump vec4 bg = texture(tex_bg, uv2);\n"
 #endif
-        "   if (fg.a == 1.0/255.0) { frag = bg; return; }\n"
+        "   if (fg.a < 1.0/255.0) { frag = bg; return; }\n"
         "   mediump float contribution = max((1.0 - bg.a) * fg.a, 1.0/255.0);\n"
         "   mediump float alpha_tot = bg.a + contribution;"
         "   mediump vec3 rgb = mix(bg.rgb, fg.rgb, fg.a / alpha_tot);\n"
diff --git a/engine/canvas.h b/engine/canvas.h
index 58ab58e..19849ba 100644
--- a/engine/canvas.h
+++ b/engine/canvas.h
@@ -49,6 +49,7 @@ class Canvas
 public:
     static Canvas* I;
     bool m_alpha_lock = false;
+    bool m_touch_lock = true;
     glm::mat4 m_mv;
     glm::mat4 m_proj;
     glm::vec4 m_box;
diff --git a/engine/event.h b/engine/event.h
index a5d6341..c081a5f 100644
--- a/engine/event.h
+++ b/engine/event.h
@@ -47,6 +47,13 @@ enum class kEventType : uint8_t
     ButtonUp,
 };
 
+enum class kEventSource : uint8_t
+{
+    Mouse,
+    Touch,
+    Stylus,
+};
+
 class Event
 {
 public:
@@ -59,8 +66,9 @@ class MouseEvent : public Event
 public:
     MouseEvent() { m_cat = kEventCategory::MouseEvent; }
     glm::vec2 m_pos;
-    float m_pressure;
-    float m_scroll_delta;
+    float m_pressure = 0;
+    float m_scroll_delta = 0;
+    kEventSource m_source = kEventSource::Mouse;
 };
 
 class KeyEvent : public Event
diff --git a/engine/node_canvas.cpp b/engine/node_canvas.cpp
index 835553c..27beec6 100644
--- a/engine/node_canvas.cpp
+++ b/engine/node_canvas.cpp
@@ -234,8 +234,9 @@ kEventResult NodeCanvas::handle_event(Event* e)
     case kEventType::MouseUpR:
     case kEventType::MouseMove:
     case kEventType::MouseCancel:
-        for (auto& mode : *m_canvas->m_mode)
-            mode->on_MouseEvent(me, loc);
+        if (!(m_canvas->m_touch_lock && me->m_source == kEventSource::Touch))
+            for (auto& mode : *m_canvas->m_mode)
+                mode->on_MouseEvent(me, loc);
         break;
     case kEventType::KeyDown:
         //             if (ke->m_key == kKey::KeyE)
diff --git a/engine/node_slider.cpp b/engine/node_slider.cpp
index 49c1c5b..d402bb3 100644
--- a/engine/node_slider.cpp
+++ b/engine/node_slider.cpp
@@ -98,11 +98,14 @@ kEventResult NodeSliderH::handle_event(Event* e)
         break;
     case kEventType::MouseCancel:
         mouse_release();
+        if (dragging)
+        {
+            m_value = m_old_value;
+            set_value(glm::length(m_value));
+            if (on_value_changed)
+                on_value_changed(this, glm::length(m_value));
+        }
         dragging = false;
-        m_value = m_old_value;
-        set_value(glm::length(m_value));
-        if (on_value_changed)
-            on_value_changed(this, glm::length(m_value));
         break;
     default:
         return kEventResult::Available;