Add grey styling for locked/disabled sliders and controls

negpy/desktop/view/styles/modern_dark.qss

@@ -124,6 +124,17 @@ QSlider::sub-page:horizontal {
     border-radius: 3px;
 }
 
+/* Disabled state — grey out locked/overridden controls. Relies entirely on
+   Qt's automatic isEnabled()-driven :disabled propagation from a parent
+   widget.setEnabled(False); no per-callsite changes needed. */
+QSlider::handle:horizontal:disabled { background: #555555; }
+QSlider::groove:horizontal:disabled { background: #1A1A1A; }
+QSlider::sub-page:horizontal:disabled { background: #2A2A2A; }
+
+QSlider#cyan_slider::handle:horizontal:disabled,
+QSlider#magenta_slider::handle:horizontal:disabled,
+QSlider#yellow_slider::handle:horizontal:disabled { background: #555555; }
+
 QListView {
     background-color: #0D0D0D;
     border: 1px solid #262626;
@@ -183,6 +194,14 @@ QComboBox:focus, QLineEdit:focus, QDoubleSpinBox:focus, QSpinBox:focus, QTextEdi
     background-color: #0D0D0D;
 }
 
+QComboBox:disabled, QLineEdit:disabled, QDoubleSpinBox:disabled, QSpinBox:disabled, QTextEdit:disabled {
+    color: #555555;
+    border: 1px solid #1A1A1A;
+}
+
+QPushButton:disabled, QToolButton:disabled { color: #555555; }
+QCheckBox:disabled { color: #555555; }
+
 QStatusBar {
     background-color: #B71C1C;
     color: white;

negpy/desktop/view/widgets/sliders.py

@@ -292,7 +292,14 @@ def setValue(self, value: float) -> None:
         super().setValue(value)
         self._update_edited_state()
 
+    def setEnabled(self, enabled: bool) -> None:
+        super().setEnabled(enabled)
+        self._update_edited_state()
+
     def _update_edited_state(self) -> None:
+        if not self.isEnabled():
+            self.label.setStyleSheet(slider_label_qss(THEME.text_muted, edited=False))
+            return
         edited = abs(self.spin.value() - self._default) > 1e-6
         self.label.setStyleSheet(slider_label_qss(self._label_color, edited))
 
@@ -347,10 +354,13 @@ def __init__(self, label: str, default_val: float = 0.0, parent=None):
 
     def _apply_hue(self, hue_deg: float) -> None:
         """Update slider handle to match the current hue; label stays grey (yellow when edited)."""
-        h = int(hue_deg) % 360
-        color = QColor.fromHsv(h, 200, 210)
+        if self.isEnabled():
+            h = int(hue_deg) % 360
+            color = QColor.fromHsv(h, 200, 210).name()
+        else:
+            color = THEME.text_muted
         self._update_edited_state()
-        self.slider.setStyleSheet(slider_handle_qss(color.name()))
+        self.slider.setStyleSheet(slider_handle_qss(color))
 
     def _on_slider_changed(self, value: int) -> None:
         super()._on_slider_changed(value)
@@ -360,6 +370,10 @@ def setValue(self, value: float) -> None:
         super().setValue(value)
         self._apply_hue(value)
 
+    def setEnabled(self, enabled: bool) -> None:
+        super().setEnabled(enabled)
+        self._apply_hue(self.value())
+
 
 def _kelvin_handle_color(kelvin: float) -> QColor:
     """Blackbody colour (Tanner Helland approximation), softened to the same
@@ -394,7 +408,8 @@ def _from_int(self, i: int) -> float:
         return round(1e6 / (i / 10.0) / 10.0) * 10.0
 
     def _apply_temp(self, kelvin: float) -> None:
-        self.slider.setStyleSheet(slider_handle_qss(_kelvin_handle_color(kelvin).name()))
+        color = _kelvin_handle_color(kelvin).name() if self.isEnabled() else THEME.text_muted
+        self.slider.setStyleSheet(slider_handle_qss(color))
 
     def _on_slider_changed(self, value: int) -> None:
         super()._on_slider_changed(value)
@@ -404,6 +419,10 @@ def setValue(self, value: float) -> None:
         super().setValue(value)
         self._apply_temp(self.value())
 
+    def setEnabled(self, enabled: bool) -> None:
+        super().setEnabled(enabled)
+        self._apply_temp(self.value())
+
 
 class RangeSlider(QWidget):
     """

tests/test_slider_widgets.py

@@ -3,6 +3,7 @@
 from PyQt6.QtCore import QEvent, QPointF, Qt
 from PyQt6.QtGui import QMouseEvent
 
+from negpy.desktop.view.styles.theme import THEME
 from negpy.desktop.view.widgets.sliders import CompactSlider, KelvinSlider
 
 
@@ -92,6 +93,31 @@ def test_kelvin_slider_handle_tracks_temperature(qapp):
     s.timer.stop()
 
 
+def test_compact_slider_locked_style_overrides_edited(qapp):
+    slider = CompactSlider("Density", 0.0, 2.0, 1.0)
+    slider.setValue(1.5)  # edited (differs from default)
+
+    slider.setEnabled(False)
+    assert THEME.text_muted in slider.label.styleSheet()
+    assert THEME.accent_edited not in slider.label.styleSheet()
+
+    slider.setEnabled(True)
+    assert THEME.accent_edited in slider.label.styleSheet()
+
+
+def test_kelvin_slider_locked_handle_is_muted(qapp):
+    s = KelvinSlider("Temperature")
+    live_qss = s.slider.styleSheet()
+
+    s.setEnabled(False)
+    assert THEME.text_muted in s.slider.styleSheet()
+    assert s.slider.styleSheet() != live_qss
+
+    s.setEnabled(True)
+    assert s.slider.styleSheet() == live_qss
+    s.timer.stop()
+
+
 def test_kelvin_slider_default_roundtrips_exactly(qapp):
     s = KelvinSlider("Temperature")
     s.setValue(4300)