diff --git a/plugins/editor/src/editor/Editor.cpp b/plugins/editor/src/editor/Editor.cpp
index 14987bf1..173d7166 100644
--- a/plugins/editor/src/editor/Editor.cpp
+++ b/plugins/editor/src/editor/Editor.cpp
@@ -164,6 +164,7 @@ struct Editor::Impl : EditorController::Receiver, IControlListener {
     void updateTuningFrequencyLabel(float tuningFrequency);
     void updateStretchedTuningLabel(float stretchedTuning);
 
+    void updateKeyUsed(unsigned key, bool used);
     void updateCCUsed(unsigned cc, bool used);
     void updateCCValue(unsigned cc, float value);
     void updateCCDefaultValue(unsigned cc, float value);
@@ -394,7 +395,12 @@ void Editor::Impl::uiReceiveMessage(const char* path, const char* sig, const sfi
     unsigned indices[8];
 
     if (Messages::matchOSC("/key/slots", path, indices) && !strcmp(sig, "b")) {
-        // TODO(jpc) key ranges
+        size_t numBits = 8 * args[0].b->size;
+        ConstBitSpan bits { args[0].b->data, numBits };
+        for (unsigned key = 0; key < 128; ++key) {
+            bool used = key < numBits && bits.test(key);
+            updateKeyUsed(key, used);
+        }
     }
     else if (Messages::matchOSC("/cc/slots", path, indices) && !strcmp(sig, "b")) {
         size_t numBits = 8 * args[0].b->size;
@@ -1274,6 +1280,12 @@ void Editor::Impl::updateStretchedTuningLabel(float stretchedTuning)
     label->setText(text);
 }
 
+void Editor::Impl::updateKeyUsed(unsigned key, bool used)
+{
+    if (SPiano* piano = piano_)
+        piano->setKeyUsed(key, used);
+}
+
 void Editor::Impl::updateCCUsed(unsigned cc, bool used)
 {
     if (SControlsPanel* panel = controlsPanel_)
diff --git a/plugins/editor/src/editor/GUIPiano.cpp b/plugins/editor/src/editor/GUIPiano.cpp
index 2c17ddc4..b2c00459 100644
--- a/plugins/editor/src/editor/GUIPiano.cpp
+++ b/plugins/editor/src/editor/GUIPiano.cpp
@@ -5,6 +5,7 @@
 // If not, contact the sfizz maintainers at https://github.com/sfztools/sfizz
 
 #include "GUIPiano.h"
+#include "ColorHelpers.h"
 #include "utility/vstgui_before.h"
 #include "vstgui/lib/cdrawcontext.h"
 #include "vstgui/lib/cgraphicspath.h"
@@ -37,6 +38,18 @@ void SPiano::setNumOctaves(unsigned octs)
     invalid();
 }
 
+void SPiano::setKeyUsed(unsigned key, bool used)
+{
+    if (key >= 128)
+        return;
+
+    if (keyUsed_.test(key) == used)
+        return;
+
+    keyUsed_.set(key, used);
+    invalid();
+}
+
 void SPiano::draw(CDrawContext* dc)
 {
     const Dimensions dim = getDimensions(false);
@@ -56,9 +69,17 @@ void SPiano::draw(CDrawContext* dc)
     for (unsigned key = 0; key < keyCount; ++key) {
         if (!black[key % 12]) {
             CRect rect = keyRect(key);
-            CColor keycolor = whiteFill_;
+
+            SColorHCY hcy(keyUsedHue_, 1.0, whiteKeyLuma_);
+            if (!keyUsed_[key]) {
+                hcy.y = 1.0;
+                if (keyval_[key])
+                    hcy.c = 0.0;
+            }
             if (keyval_[key])
-                keycolor = pressedFill_;
+                hcy.y = std::max(0.0f, hcy.y - keyLumaPressDelta_);
+
+            CColor keycolor = hcy.toColor();
             dc->setFillColor(keycolor);
             dc->drawRect(rect, kDrawFilled);
         }
@@ -76,9 +97,14 @@ void SPiano::draw(CDrawContext* dc)
     for (unsigned key = 0; key < keyCount; ++key) {
         if (black[key % 12]) {
             CRect rect = keyRect(key);
-            CColor keycolor = blackFill_;
+
+            SColorHCY hcy(keyUsedHue_, 1.0, blackKeyLuma_);
+            if (!keyUsed_[key])
+                hcy.c = 0.0;
             if (keyval_[key])
-                keycolor = pressedFill_;
+                hcy.y = std::max(0.0f, hcy.y - keyLumaPressDelta_);
+
+            CColor keycolor = hcy.toColor();
             dc->setFillColor(keycolor);
             dc->drawRect(rect, kDrawFilled);
             dc->setFrameColor(outline_);
diff --git a/plugins/editor/src/editor/GUIPiano.h b/plugins/editor/src/editor/GUIPiano.h
index 6927b06f..13e3ac4e 100644
--- a/plugins/editor/src/editor/GUIPiano.h
+++ b/plugins/editor/src/editor/GUIPiano.h
@@ -11,6 +11,7 @@
 #include "utility/vstgui_after.h"
 #include <functional>
 #include <vector>
+#include <bitset>
 
 using namespace VSTGUI;
 
@@ -24,6 +25,8 @@ public:
     unsigned getNumOctaves() const { return octs_; }
     void setNumOctaves(unsigned octs);
 
+    void setKeyUsed(unsigned key, bool used);
+
     std::function<void(unsigned, float)> onKeyPressed;
     std::function<void(unsigned, float)> onKeyReleased;
 
@@ -52,6 +55,7 @@ private:
 private:
     unsigned octs_ {};
     std::vector<unsigned> keyval_;
+    std::bitset<128> keyUsed_;
     unsigned mousePressedKey_ = ~0u;
 
     CCoord innerPaddingX_ = 4.0;
@@ -60,9 +64,12 @@ private:
 
     CColor backgroundFill_ { 0xca, 0xca, 0xca, 0xff };
     float backgroundRadius_ = 5.0;
-    CColor whiteFill_ { 0xee, 0xee, 0xec, 0xff };
-    CColor blackFill_ { 0x2e, 0x34, 0x36, 0xff };
-    CColor pressedFill_ { 0xa0, 0xa0, 0xa0, 0xff };
+
+    float keyUsedHue_ = 0.55;
+    float whiteKeyLuma_ = 0.5;
+    float blackKeyLuma_ = 0.25;
+    float keyLumaPressDelta_ = 0.20;
+
     CColor outline_ { 0x00, 0x00, 0x00, 0xff };
     CColor shadeOutline_ { 0x80, 0x80, 0x80, 0xff };
     CColor labelStroke_ { 0x63, 0x63, 0x63, 0xff };