Persist material editor column widths in preferences

MaterialBrowserWidth / MaterialPreviewWidth in preferences.ini, saved
from the live splitter positions on shutdown and restored (clamped to
the splitter ranges) at startup.

Co-Authored-By: Claude Fable 5 <noreply@anthropic.com>

src/ui/Application.cpp

@@ -424,11 +424,25 @@ void Application::LoadPreferences()
         else if (key == "OcioView")           m_prefs.ocioView            = val;
         else if (key == "OcioColorSpace")     m_prefs.ocioColorSpace      = val;
         else if (key == "OcioLook")           m_prefs.ocioLook            = val;
+        else if (key == "MaterialBrowserWidth")
+            m_prefs.materialBrowserWidth = [&]{ try { return std::stof(val); } catch(...){ return 220.0f; } }();
+        else if (key == "MaterialPreviewWidth")
+            m_prefs.materialPreviewWidth = [&]{ try { return std::stof(val); } catch(...){ return 320.0f; } }();
     }
+
+    if (m_materialEditorPanel)
+        m_materialEditorPanel->SetColumnWidths(m_prefs.materialBrowserWidth,
+                                               m_prefs.materialPreviewWidth);
 }
 
 void Application::SavePreferences()
 {
+    // Pull the latest splitter positions; called from Shutdown before the
+    // panel is reset, and from the preferences dialog while it's alive.
+    if (m_materialEditorPanel)
+        m_materialEditorPanel->GetColumnWidths(m_prefs.materialBrowserWidth,
+                                               m_prefs.materialPreviewWidth);
+
     std::ofstream f(m_prefsPath);
     if (!f) return;
     f << "[Preferences]\n";
@@ -438,6 +452,8 @@ void Application::SavePreferences()
     f << "OcioView="            << m_prefs.ocioView            << "\n";
     f << "OcioColorSpace="      << m_prefs.ocioColorSpace      << "\n";
     f << "OcioLook="            << m_prefs.ocioLook            << "\n";
+    f << "MaterialBrowserWidth=" << m_prefs.materialBrowserWidth << "\n";
+    f << "MaterialPreviewWidth=" << m_prefs.materialPreviewWidth << "\n";
 }
 
 void Application::ApplyPrefsToAllViewports()

src/ui/Application.h

@@ -28,6 +28,8 @@ struct AppPreferences {
     std::string ocioView;
     std::string ocioColorSpace;
     std::string ocioLook;
+    float materialBrowserWidth = 220.0f; ///< Material Editor left-column width
+    float materialPreviewWidth = 320.0f; ///< Material Editor right-column width
 };
 
 class Application {

src/ui/MaterialEditorPanel.cpp

@@ -148,6 +148,11 @@ std::vector<const ShaderNodeTypeInfo*> FilterShaderNodeTypes(
     return matches;
 }
 
+// Clamp range shared by the column splitters and SetColumnWidths (persisted
+// preferences may carry hand-edited or stale values).
+constexpr float kBrowserMinWidth = 140.0f, kBrowserMaxWidth = 500.0f;
+constexpr float kPreviewMinWidth = 220.0f, kPreviewMaxWidth = 640.0f;
+
 // Vertical drag-splitter between the material editor's columns. Adjusts
 // *width by the mouse drag (negated for a right-hand column, which grows
 // when dragged left); colours match the viewport's split dividers.
@@ -238,6 +243,11 @@ void MaterialEditorPanel::SetStage(pxr::UsdStageRefPtr stage) {
     m_browserSelection = pxr::SdfPath();
 }
 
+void MaterialEditorPanel::SetColumnWidths(float browserWidth, float previewWidth) {
+    m_browserWidth = std::clamp(browserWidth, kBrowserMinWidth, kBrowserMaxWidth);
+    m_previewWidth = std::clamp(previewWidth, kPreviewMinWidth, kPreviewMaxWidth);
+}
+
 void MaterialEditorPanel::SetColorCorrectionFromPrefs(int ccMode, const std::string& ocioDisplay,
                                                       const std::string& ocioView,
                                                       const std::string& ocioColorSpace,
@@ -261,14 +271,14 @@ void MaterialEditorPanel::Render() {
     RenderMaterialBrowser();
     ImGui::EndChild();
 
-    VerticalSplitter("##MaterialSplitL", &m_browserWidth, 140.0f, 500.0f,
+    VerticalSplitter("##MaterialSplitL", &m_browserWidth, kBrowserMinWidth, kBrowserMaxWidth,
                      /*rightSideColumn=*/false);
 
     ImGui::BeginChild("MaterialCanvasRegion", ImVec2(-(m_previewWidth + 6.0f), 0.0f), false);
     RenderNodeGraphCanvas();
     ImGui::EndChild();
 
-    VerticalSplitter("##MaterialSplitR", &m_previewWidth, 220.0f, 640.0f,
+    VerticalSplitter("##MaterialSplitR", &m_previewWidth, kPreviewMinWidth, kPreviewMaxWidth,
                      /*rightSideColumn=*/true);
 
     ImGui::BeginChild("MaterialPreviewRegion", ImVec2(0.0f, 0.0f), true);

src/ui/MaterialEditorPanel.h

@@ -44,6 +44,14 @@ public:
     /// auto-loads it into the canvas.
     void SetTargetPrimPath(const std::string& path);
 
+    /// Splitter-adjustable column widths, persisted in preferences.ini by
+    /// Application. Setter clamps to the same range as the splitters.
+    void GetColumnWidths(float& browserWidth, float& previewWidth) const {
+        browserWidth = m_browserWidth;
+        previewWidth = m_previewWidth;
+    }
+    void SetColumnWidths(float browserWidth, float previewWidth);
+
     void Render();
 
 private: