diff --git a/src/node_stroke_preview.cpp b/src/node_stroke_preview.cpp
index d001d75..614614a 100644
--- a/src/node_stroke_preview.cpp
+++ b/src/node_stroke_preview.cpp
@@ -408,7 +408,7 @@ void NodeStrokePreview::draw_stroke_immediate()
         b->m_pattern_texture->bind() :
         glBindTexture(GL_TEXTURE_2D, 0);
     glActiveTexture(GL_TEXTURE3);
-    m_rtt_mixer.bindTexture();
+    b->m_tip_mix > 0.f ? m_rtt_mixer.bindTexture() : glBindTexture(GL_TEXTURE_2D, 0);
     auto frames = stroke_draw_compute(m_stroke, zoom);
     m_rtt.clear();
     for (auto& f : frames)
diff --git a/src/rtt.cpp b/src/rtt.cpp
index 72e76de..3a5b8ed 100644
--- a/src/rtt.cpp
+++ b/src/rtt.cpp
@@ -6,7 +6,6 @@
 
 RTT& RTT::operator=(RTT&& other)
 {
-    LOG("RTT-move-assignment");
     int_fmt = other.int_fmt;
     texID = other.texID;
     fboID = other.fboID;
@@ -38,8 +37,6 @@ RTT::RTT()
 
 RTT::RTT(RTT&& other)
 {
-    LOG("RTT-move-ctor");
-
     int_fmt = other.int_fmt;
     texID = other.texID;
     fboID = other.fboID;
@@ -59,10 +56,9 @@ RTT::RTT(RTT&& other)
 
 RTT::~RTT()
 {
-    LOG("RTT-dtor");
-    //destroy();
-    if (texID || rboID || fboID)
+    if (valid())
         LOG("RTT not destroyed");
+    destroy();
 }
 
 bool RTT::resize(int width, int height)
@@ -109,6 +105,8 @@ bool RTT::resize(int width, int height)
 
 void RTT::destroy()
 {
+    if (!valid())
+        return;
     App::I->render_task_async([rboID=rboID, texID=texID, fboID=fboID]
     {
         if (rboID)
@@ -137,6 +135,8 @@ void RTT::destroy()
 
 void RTT::copy(const RTT & source)
 {
+    if (!valid() || !source.valid())
+        return;
     App::I->render_task([&]
     {
         GLint old_draw = 0;
@@ -156,6 +156,8 @@ void RTT::copy(const RTT & source)
 
 void RTT::copy(const RTT& source, const glm::vec4& rect)
 {
+    if (!valid() || !source.valid())
+        return;
     App::I->render_task([&]
     {
         auto r = rect_intersection(rect, { 0, 0, w, h });
@@ -317,6 +319,9 @@ void RTT::clear_mask(glm::bool4 mask, glm::vec4 color)
 
 glm::ivec4 RTT::calc_bounds() const noexcept
 {
+    if (!valid())
+        return glm::vec4(0);
+
     auto data = std::unique_ptr<glm::u8vec4[]>(reinterpret_cast<glm::u8vec4*>(readTextureData()));
     glm::ivec2 bbmin(w, h);
     glm::ivec2 bbmax(0);
@@ -336,6 +341,8 @@ glm::ivec4 RTT::calc_bounds() const noexcept
 
 uint8_t* RTT::readTextureData(uint8_t* buffer) const noexcept
 {
+    if (!valid())
+        return nullptr;
     if (!buffer)
         buffer = createBuffer();
     App::I->render_task([&]
@@ -351,6 +358,8 @@ uint8_t* RTT::readTextureData(uint8_t* buffer) const noexcept
 
 float* RTT::readTextureDataFloat(float* buffer) const noexcept
 {
+    if (!valid())
+        return nullptr;
     if (!buffer)
         buffer = createBufferFloat();
     App::I->render_task([&]
@@ -393,3 +402,7 @@ Image RTT::get_image() const noexcept
     return ret;
 }
 
+bool RTT::valid() const noexcept
+{
+    return texID || rboID || fboID;
+}
diff --git a/src/rtt.h b/src/rtt.h
index de77f1d..a9b6075 100644
--- a/src/rtt.h
+++ b/src/rtt.h
@@ -51,4 +51,5 @@ public:
     int stride() const noexcept { return w * 4; }
     GLuint getFBO() const noexcept { return fboID; }
     Image get_image() const noexcept;
+    bool valid() const noexcept;
 };