diff --git a/SimDirs/ContentView.swift b/SimDirs/ContentView.swift
index d7d9ce5..702f10b 100644
--- a/SimDirs/ContentView.swift
+++ b/SimDirs/ContentView.swift
@@ -17,7 +17,7 @@ struct ContentView: View {
     var body: some View {
         VStack {
             NavigationView {
-                List {
+                List(selection: $state.selection) {
                     Divider()
 
                     switch state.base {
@@ -26,12 +26,12 @@ struct ContentView: View {
 
                         case let .device(_, item):
                             ForEach(item.visibleChildren) {
-                                SourceItemGroup(selection: $state.selection, item: $0)
+                                SourceItemGroup(item: $0, selection: $state.selection)
                             }
                             
                         case let .runtime(_, item):
                             ForEach(item.visibleChildren) {
-                                SourceItemGroup(selection: $state.selection, item: $0)
+                                SourceItemGroup(item: $0, selection: $state.selection)
                             }
                     }
                 }
diff --git a/SimDirs/Presentation/SourceItem.swift b/SimDirs/Presentation/SourceItem.swift
index 40d42b2..a4e706c 100644
--- a/SimDirs/Presentation/SourceItem.swift
+++ b/SimDirs/Presentation/SourceItem.swift
@@ -16,6 +16,7 @@ protocol SourceItem: Identifiable, ObservableObject {
     var children        : [Child] { get set }
     var visibleChildren : [Child] { get set }
     var customImgDesc   : SourceImageDesc? { get }
+    var isExpanded      : Bool { get set }
 }
 
 extension SourceItem {
@@ -54,10 +55,21 @@ extension SourceItem {
 
         return match || !visibleChildren.isEmpty
     }
+
+    func toggleExpanded(_ expanded: Bool? = nil, deep: Bool) {
+        isExpanded = expanded ?? !isExpanded
+        
+        if deep {
+            for child in children {
+                child.toggleExpanded(isExpanded, deep: true)
+            }
+        }
+    }
 }
 
 class SourceItemVal<Model: SourceItemData, Child: SourceItem>: SourceItem {
     @Published var visibleChildren  : [Child]
+    @Published var isExpanded       : Bool
     
     var id              = UUID()
     var data            : Model
@@ -70,6 +82,7 @@ class SourceItemVal<Model: SourceItemData, Child: SourceItem>: SourceItem {
         self.children = children
         self.visibleChildren = children
         self.customImgDesc = customImgDesc
+        self.isExpanded = false
     }
 }
 
@@ -78,4 +91,5 @@ class SourceItemNone: SourceItem {
     var data            = SourceItemDataNone()
     var children        = [SourceItemNone]()
     var visibleChildren = [SourceItemNone]()
+    var isExpanded      = false
 }
diff --git a/SimDirs/Views/SourceItem Views/SourceItemGroup.swift b/SimDirs/Views/SourceItem Views/SourceItemGroup.swift
index eeaf198..cef317f 100644
--- a/SimDirs/Views/SourceItem Views/SourceItemGroup.swift	
+++ b/SimDirs/Views/SourceItem Views/SourceItemGroup.swift	
@@ -8,25 +8,41 @@
 import SwiftUI
 
 struct SourceItemGroup<Item: SourceItem>: View {
-    @State private var isExpanded = false   // would like to move into Item
-    @Binding var selection: UUID?
-    @StateObject var item: Item
+    @StateObject var item               : Item
+    @Binding var selection              : UUID?
 
     var body: some View {
-        if item.visibleChildren.count > 0 {
-            DisclosureGroup(
-                isExpanded: $isExpanded) {
-                    ForEach(item.visibleChildren) { childItem in
-                        SourceItemGroup<Item.Child>(selection: $selection, item: childItem)
-                    }
-                } label: {
-                    SourceItemLink(selection: $selection, item: item)
-                }
+        HStack(spacing: 0) {
+            let button = Button(action: {
+                let optionActive = NSApplication.shared.currentEvent?.modifierFlags.contains(.option) == true
                 
-        }
-        else {
+                withAnimation(.easeInOut(duration: 0.2)) {
+                    item.toggleExpanded(deep: optionActive)
+                }
+            }, label: {
+                Image(systemName: "chevron.right")
+                    .padding(.horizontal, 2.0)
+                    .contentShape(Rectangle())
+                    .rotationEffect(.degrees(item.isExpanded ? 90.0 : 0.0))
+            })
+            .buttonStyle(.plain)
+            
+            if item.visibleChildren.count == 0 {
+                button.hidden()
+            }
+            else {
+                button
+            }
+            
             SourceItemLink(selection: $selection, item: item)
         }
+        
+        if item.isExpanded {
+            ForEach(item.visibleChildren) { childItem in
+                SourceItemGroup<Item.Child>(item: childItem, selection: $selection)
+            }
+            .padding(.leading, 12.0)
+        }
     }
 }
 
@@ -36,6 +52,10 @@ struct SourceItemGroup_Previews: PreviewProvider {
     static var sampleItem = state.deviceStyleItems()[0]
 
     static var previews: some View {
-        SourceItemGroup(selection: $selection, item: sampleItem)
+        List {
+            SourceItemGroup(item: sampleItem, selection: $selection)
+            SourceItemGroup(item: sampleItem, selection: $selection)
+            SourceItemGroup(item: sampleItem, selection: $selection)
+        }
     }
 }
diff --git a/SimDirs/Views/SourceItem Views/SourceItemLink.swift b/SimDirs/Views/SourceItem Views/SourceItemLink.swift
index 10cb7be..fe7e47f 100644
--- a/SimDirs/Views/SourceItem Views/SourceItemLink.swift	
+++ b/SimDirs/Views/SourceItem Views/SourceItemLink.swift	
@@ -15,10 +15,7 @@ struct SourceItemLink<Item: SourceItem>: View {
     var body: some View {
         NavigationLink(tag: item.id, selection: $selection,
             destination: { SourceItemContent(item: item) },
-            label: {
-                SourceItemLabel(item: item)
-                    .padding(.leading, 2.0)
-            }
+            label: { SourceItemLabel(item: item) }
         )
     }
 }