diff --git a/data/layout.xml b/data/layout.xml
index 72377e1..6455458 100644
--- a/data/layout.xml
+++ b/data/layout.xml
@@ -349,7 +349,7 @@
         </node>
       </border>
       <!-- toolbar -->
-      <border id="toolbar" height="50" width="100%" pad="5" dir="row" color=".2">
+      <border id="toolbar" height="50" width="100%" pad="5" dir="row" color=".2 .2 .2 .6">
         <button id="btn-open" width="50" height="100%" margin="0 5 0 0" text="Open"/>
         <button id="btn-save" width="50" height="100%" margin="0 5 0 0" text="Save"/>
         <button id="btn-export" width="50" height="100%" margin="0 5 0 0" text="Export"/>
diff --git a/engine/app.cpp b/engine/app.cpp
index ec039f3..dfefcff 100644
--- a/engine/app.cpp
+++ b/engine/app.cpp
@@ -195,6 +195,28 @@ void App::initShaders()
         "   mediump vec3 rgb = mix(bg.rgb, fg.rgb, fg.a / alpha_tot);\n"
         "   frag = vec4(rgb, alpha_tot);\n"
         "}\n";
+    // ALPHA LOCK
+    static const char* shader_stroke_lock_f =
+        SHADER_VERSION
+        "uniform mediump sampler2D tex;\n"
+        "uniform mediump sampler2D tex_bg;\n"
+        "uniform mediump sampler2D tex_mask;\n"
+        "uniform mediump vec4 col;\n"
+        "uniform mediump vec2 resolution;\n"
+        "uniform mediump float alpha;\n"
+        "in mediump vec2 uv;\n"
+        "out mediump vec4 frag;\n"
+        "void main(){\n"
+        "   mediump vec2 uv2 = gl_FragCoord.st / resolution;\n"
+        "   mediump float brush_alpha = ( 1.0 - texture(tex, uv).r ) * alpha;\n"
+        "   mediump vec4 fg = vec4(col.rgb, brush_alpha);\n"
+        "   mediump vec4 bg = texture(tex_bg, uv2);\n"
+        "   mediump vec4 msk = texture(tex_mask, uv2);\n"
+        "   if (fg.a < (1.0/255.0)) { frag = bg; return; }\n"
+        "   mediump float alpha_tot = fg.a + (1.0 - fg.a) * bg.a;"
+        "   mediump vec3 rgb = mix(bg.rgb, fg.rgb, fg.a / alpha_tot);\n"
+        "   frag = vec4(rgb, min(alpha_tot, msk.a));\n"
+        "}\n";
     // ERASER
     static const char* shader_stroke_erase_f =
         SHADER_VERSION
@@ -310,6 +332,8 @@ void App::initShaders()
         LOG("Failed to create shader Atlas");
     if (!ShaderManager::create(kShader::Stroke, shader_stroke_v, shader_stroke_f))
         LOG("Failed to create shader Stroke");
+    if (!ShaderManager::create(kShader::StrokeLock, shader_stroke_v, shader_stroke_lock_f))
+        LOG("Failed to create shader StrokeLock");
     if (!ShaderManager::create(kShader::StrokeErase, shader_stroke_v, shader_stroke_erase_f))
         LOG("Failed to create shader StrokeErase");
     if (!ShaderManager::create(kShader::StrokeLayer, shader_stroke_layer_v, shader_stroke_layer_f))
@@ -432,6 +456,10 @@ void App::initLayout()
             canvas->m_canvas->m_layers[idx].m_opacity = value;
         };
 
+        layers->on_layer_visibility_changed = [this](Node*, int idx, bool visible) {
+            canvas->m_canvas->m_layers[canvas->m_canvas->m_order[idx]].m_alpha_locked = visible;
+        };
+
         if (auto* button = layout[main_id]->find<NodeButtonCustom>("btn-bucket"))
         {
             button->on_click = [this](Node*) {
@@ -602,7 +630,7 @@ void App::initLayout()
 
 void App::initLog()
 {
-    //LogRemote::I.start();
+    LogRemote::I.start();
 }
 void App::init()
 {
diff --git a/engine/canvas.cpp b/engine/canvas.cpp
index 936fd2b..6bbcc1d 100644
--- a/engine/canvas.cpp
+++ b/engine/canvas.cpp
@@ -68,6 +68,7 @@ void ui::Canvas::stroke_draw()
     tex.bind();
     m_sampler.bind(0);
     m_sampler_bg.bind(1);
+    m_sampler_mask.bind(2);
     
     for (int i = 0; i < 6; i++)
     {
@@ -92,6 +93,15 @@ void ui::Canvas::stroke_draw()
                 ShaderManager::use(ui::kShader::StrokeErase);
                 //ShaderManager::u_vec4(kShaderUniform::Col, m_brush.m_tip_color);
             }
+            else if(m_layers[m_current_layer_idx].m_alpha_locked)
+            {
+                ShaderManager::use(kShader::StrokeLock);
+                ShaderManager::u_vec4(kShaderUniform::Col, m_brush.m_tip_color);
+                ShaderManager::u_int(kShaderUniform::TexMask, 2); // alpha mask
+                glActiveTexture(GL_TEXTURE2);
+                m_layers[m_current_layer_idx].m_rtt[i].bindTexture();
+                glActiveTexture(GL_TEXTURE1);
+            }
             else
             {
                 ShaderManager::use(ui::kShader::Stroke);
@@ -195,16 +205,25 @@ void ui::Canvas::stroke_draw()
                 m_plane_brush.draw_fill();
             }
         }
+
+        if (m_alpha_lock)
+        {
+            glActiveTexture(GL_TEXTURE2);
+            m_layers[m_current_layer_idx].m_rtt[i].unbindTexture();
+        }
         
+        glActiveTexture(GL_TEXTURE1);
         m_tex[i].unbind();
+
         m_tmp[i].unbindFramebuffer();
     }
     
     glDisable(GL_BLEND);
-    
+
     glActiveTexture(GL_TEXTURE0);
     m_sampler.unbind();
     m_sampler_bg.unbind();
+    m_sampler_mask.unbind();
     tex.unbind();
     
     glViewport(vp[0], vp[1], vp[2], vp[3]);
@@ -361,6 +380,7 @@ bool ui::Canvas::create(int width, int height)
     }
     m_sampler.create();
     m_sampler_bg.create();
+    m_sampler_mask.create();
     m_plane.create<1>(1, 1);
     m_plane_brush.create<1>(1, 1);
     m_mesh.create();
diff --git a/engine/canvas.h b/engine/canvas.h
index 804917c..56896cb 100644
--- a/engine/canvas.h
+++ b/engine/canvas.h
@@ -13,7 +13,7 @@ class Layer
 public:
     RTT m_rtt[6];
     bool m_visible = true;
-    bool m_locked = false;
+    bool m_alpha_locked = false;
     float m_opacity = 1.f;
     std::string m_name;
     struct Snapshot
@@ -41,6 +41,7 @@ class Canvas
 public:
     static Canvas* I;
     bool m_erase = false;
+    bool m_alpha_lock = false;
     glm::mat4 m_mv;
     glm::mat4 m_proj;
     glm::vec4 m_box;
@@ -63,6 +64,7 @@ public:
     static glm::mat4 m_plane_transform[6];
     Sampler m_sampler;
     Sampler m_sampler_bg;
+    Sampler m_sampler_mask;
     glm::vec2 m_cam_rot;
     float m_cam_fov = 85;
 
diff --git a/engine/keymap.h b/engine/keymap.h
index 4b18265..d76b0c9 100644
--- a/engine/keymap.h
+++ b/engine/keymap.h
@@ -263,7 +263,7 @@ kKey convert_key(int key)
     CASE(VK_NONCONVERT, kKey::Unknown);
     CASE(VK_ACCEPT, kKey::Unknown);
     CASE(VK_MODECHANGE, kKey::Unknown);
-    CASE(VK_SPACE, kKey::Unknown);
+    CASE(VK_SPACE, kKey::KeySpacebar);
     CASE(VK_PRIOR, kKey::Unknown);
     CASE(VK_NEXT, kKey::Unknown);
     CASE(VK_END, kKey::Unknown);
diff --git a/engine/layout.h b/engine/layout.h
index 1a857e1..74901c0 100644
--- a/engine/layout.h
+++ b/engine/layout.h
@@ -1192,6 +1192,7 @@ public:
 class NodeCheckBox : public Node
 {
 public:
+    std::function<void(Node* target, bool checked)> on_value_changed;
     NodeBorder* m_outer;
     NodeBorder* m_inner;
     bool checked = false;
@@ -1244,6 +1245,8 @@ public:
             break;
         case kEventType::MouseUpL:
             checked = !checked;
+            if (on_value_changed)
+                on_value_changed(this, checked);
             break;
         default:
             return kEventResult::Available;
@@ -1263,6 +1266,7 @@ class NodeLayer : public NodeBorder
 public:
     std::function<void(NodeLayer* target)> on_selected;
     std::function<void(NodeLayer* target, float opacity)> on_opacity_changed;
+    std::function<void(NodeLayer* target, bool visible)> on_visibility_changed;
     bool m_selected = false;
     glm::vec4 m_color_normal = glm::vec4(.4, .4, .4, 1);
     glm::vec4 m_color_selected = glm::vec4(.3, .3, .3, 1);
@@ -1319,6 +1323,10 @@ public:
             if (on_opacity_changed)
                 on_opacity_changed(this, value);
         };
+        m_visibility->on_value_changed = [this](Node*, bool checked) {
+            if (on_visibility_changed)
+                on_visibility_changed(this, checked);
+        };
     }
     virtual kEventResult handle_event(Event* e) override
     {
@@ -1366,6 +1374,7 @@ class NodePanelLayer : public Node
 public:
     std::function<void(Node* target, int old_idx, int new_idx)> on_layer_change;
     std::function<void(Node* target, int idx, float value)> on_layer_opacity_changed;
+    std::function<void(Node* target, int idx, bool visible)> on_layer_visibility_changed;
     std::function<void(Node* target, int index)> on_layer_delete;
     std::function<void(Node* target)> on_layer_add;
     std::function<void(Node* target, int old_idx, int new_idx)> on_layer_order;
@@ -1439,6 +1448,7 @@ public:
         l->set_name(name);
         l->on_selected = std::bind(&NodePanelLayer::handle_layer_selected, this, std::placeholders::_1);
         l->on_opacity_changed = std::bind(&NodePanelLayer::handle_layer_opacity, this, std::placeholders::_1, std::placeholders::_2);
+        l->on_visibility_changed = std::bind(&NodePanelLayer::handle_layer_visibility, this, std::placeholders::_1, std::placeholders::_2);
         m_layers.push_back(l);
     }
     void remove_layer(NodeLayer* layer)
@@ -1460,6 +1470,11 @@ public:
         if (on_layer_opacity_changed)
             on_layer_opacity_changed(this, m_layers_container->get_child_index(target), value);
     }
+    void handle_layer_visibility(NodeLayer* target, bool visible)
+    {
+        if (on_layer_visibility_changed)
+            on_layer_visibility_changed(this, m_layers_container->get_child_index(target), visible);
+    }
     void handle_layer_selected(NodeLayer* target)
     {
         if (m_current_layer)
@@ -1945,7 +1960,6 @@ class NodeCanvas : public Node
     float m_camera_fov;
     float m_zoom_canvas = 1.f;
     float m_zoom_start;
-    bool method = true;
 public:
     std::string data_path;
     std::unique_ptr<ui::Canvas> m_canvas;
@@ -2033,7 +2047,6 @@ public:
                 }
                 if (m_canvas->m_show_tmp && m_canvas->m_current_layer_idx == layer_index)
                 {
-                    glEnable(GL_BLEND);
                     ui::ShaderManager::u_float(kShaderUniform::Alpha, 
                         m_canvas->m_current_stroke->m_brush.m_tip_opacity * m_canvas->m_layers[layer_index].m_opacity);
                     m_canvas->m_tmp[plane_index].bindTexture();
@@ -2112,10 +2125,9 @@ public:
             break;
         case kEventType::KeyDown:
             if (ke->m_key == kKey::KeyE)
-            {
                 m_canvas->m_erase = true;
-                method = !method;
-            }
+            if (ke->m_key == kKey::KeySpacebar)
+                m_canvas->m_alpha_lock = true;
             if (ke->m_key == kKey::AndroidVolumeUp)
                 m_zoom_canvas *= 0.9f;
             if (ke->m_key == kKey::AndroidVolumeDown)
@@ -2124,6 +2136,8 @@ public:
         case kEventType::KeyUp:
             if (ke->m_key == kKey::KeyE)
                 m_canvas->m_erase = false;
+            if (ke->m_key == kKey::KeySpacebar)
+                m_canvas->m_alpha_lock = false;
             break;
         case kEventType::GestureStart:
             m_pan_start = m_pan;
diff --git a/engine/shader.h b/engine/shader.h
index 09b0535..2a94c8b 100644
--- a/engine/shader.h
+++ b/engine/shader.h
@@ -9,6 +9,7 @@ enum class kShaderUniform : uint16_t
     Tex = const_hash("tex"),
     TexFG = const_hash("tex_fg"),
     TexBG = const_hash("tex_bg"),
+    TexMask = const_hash("tex_mask"),
     Col = const_hash("col"),
     Tof = const_hash("tof"),
     Tsz = const_hash("tsz"),
@@ -27,10 +28,11 @@ enum class kShader : uint16_t
     Font        = const_hash("font"),
     Atlas       = const_hash("atlas"),
     Stroke      = const_hash("stroke"),
+    StrokeLock = const_hash("stroke-lock"),
     StrokeErase = const_hash("stroke-erase"),
     StrokeLayer = const_hash("stroke-layer"),
     Checkerboard= const_hash("checkerboard"),
-    Equirect    = const_hash("equirect"),
+    Equirect = const_hash("equirect"),
 };
 
 class Shader