diff --git a/Packages/vChewing_CandidateWindow/Sources/CandidateWindow/CandidatePool.swift b/Packages/vChewing_CandidateWindow/Sources/CandidateWindow/CandidatePool.swift
index 6be973b0..2b15cc3c 100644
--- a/Packages/vChewing_CandidateWindow/Sources/CandidateWindow/CandidatePool.swift
+++ b/Packages/vChewing_CandidateWindow/Sources/CandidateWindow/CandidatePool.swift
@@ -10,7 +10,7 @@ import Cocoa
 import Shared
 
 /// 候選字窗會用到的資料池單位。
-public class CandidatePool {
+public struct CandidatePool {
   public let blankCell = CandidateCellData(key: " ", displayedText: "　", isSelected: false)
   public var currentLayout: NSUserInterfaceLayoutOrientation = .horizontal
   public private(set) var candidateDataAll: [CandidateCellData] = []
@@ -174,7 +174,7 @@ public class CandidatePool {
 
   // MARK: Public Functions
 
-  public func selectNewNeighborLine(isForward: Bool) {
+  public mutating func selectNewNeighborLine(isForward: Bool) {
     switch currentLayout {
       case .horizontal: selectNewNeighborRow(direction: isForward ? .down : .up)
       case .vertical: selectNewNeighborColumn(direction: isForward ? .right : .left)
@@ -182,7 +182,7 @@ public class CandidatePool {
     }
   }
 
-  public func highlight(at indexSpecified: Int) {
+  public mutating func highlight(at indexSpecified: Int) {
     switch currentLayout {
       case .horizontal: highlightHorizontal(at: indexSpecified)
       case .vertical: highlightVertical(at: indexSpecified)
@@ -221,7 +221,7 @@ extension CandidatePool {
     currentColumnNumber..<min(candidateColumns.count, currentColumnNumber + maxColumnsPerPage)
   }
 
-  private func selectNewNeighborRow(direction: VerticalDirection) {
+  private mutating func selectNewNeighborRow(direction: VerticalDirection) {
     let currentSubIndex = candidateDataAll[highlightedIndex].subIndex
     var result = currentSubIndex
     switch direction {
@@ -259,7 +259,7 @@ extension CandidatePool {
     }
   }
 
-  private func selectNewNeighborColumn(direction: HorizontalDirection) {
+  private mutating func selectNewNeighborColumn(direction: HorizontalDirection) {
     let currentSubIndex = candidateDataAll[highlightedIndex].subIndex
     switch direction {
       case .left:
@@ -288,7 +288,7 @@ extension CandidatePool {
     }
   }
 
-  private func highlightHorizontal(at indexSpecified: Int) {
+  private mutating func highlightHorizontal(at indexSpecified: Int) {
     var indexSpecified = indexSpecified
     highlightedIndex = indexSpecified
     if !(0..<candidateDataAll.count).contains(highlightedIndex) {
@@ -321,7 +321,7 @@ extension CandidatePool {
     }
   }
 
-  private func highlightVertical(at indexSpecified: Int) {
+  private mutating func highlightVertical(at indexSpecified: Int) {
     var indexSpecified = indexSpecified
     highlightedIndex = indexSpecified
     if !(0..<candidateDataAll.count).contains(highlightedIndex) {
diff --git a/Packages/vChewing_CandidateWindow/Sources/CandidateWindow/TDKCandidates/CtlCandidateTDK.swift b/Packages/vChewing_CandidateWindow/Sources/CandidateWindow/TDKCandidates/CtlCandidateTDK.swift
index 491f2088..9464f660 100644
--- a/Packages/vChewing_CandidateWindow/Sources/CandidateWindow/TDKCandidates/CtlCandidateTDK.swift
+++ b/Packages/vChewing_CandidateWindow/Sources/CandidateWindow/TDKCandidates/CtlCandidateTDK.swift
@@ -13,52 +13,54 @@ import SwiftUI
 
 @available(macOS 10.15, *)
 public class CtlCandidateTDK: CtlCandidate {
-  public var thePoolHorizontal: CandidatePool = .init(candidates: [], rowCapacity: 6)
-  public var thePoolVertical: CandidatePool = .init(candidates: [], columnCapacity: 6)
   public var maxLinesPerPage: Int = 0
 
+  private static var thePoolHorizontal: CandidatePool = .init(candidates: [], rowCapacity: 6)
+  private static var thePoolVertical: CandidatePool = .init(candidates: [], columnCapacity: 6)
+  private static var currentView: NSView = .init()
+
   @available(macOS 12, *)
-  public var theViewHorizontal: VwrCandidateHorizontal {
-    .init(
-      controller: self, thePool: thePoolHorizontal,
+  private var theViewHorizontal: some View {
+    VwrCandidateHorizontal(
+      controller: self, thePool: Self.thePoolHorizontal,
       tooltip: tooltip, reverseLookupResult: reverseLookupResult
-    )
+    ).edgesIgnoringSafeArea(.top)
   }
 
   @available(macOS 12, *)
-  public var theViewVertical: VwrCandidateVertical {
-    .init(
-      controller: self, thePool: thePoolVertical,
+  private var theViewVertical: some View {
+    VwrCandidateVertical(
+      controller: self, thePool: Self.thePoolVertical,
       tooltip: tooltip, reverseLookupResult: reverseLookupResult
-    )
+    ).edgesIgnoringSafeArea(.top)
   }
 
-  public var theViewHorizontalBackports: VwrCandidateHorizontalBackports {
-    .init(
-      controller: self, thePool: thePoolHorizontal,
+  private var theViewHorizontalBackports: some View {
+    VwrCandidateHorizontalBackports(
+      controller: self, thePool: Self.thePoolHorizontal,
       tooltip: tooltip, reverseLookupResult: reverseLookupResult
-    )
+    ).edgesIgnoringSafeArea(.top)
   }
 
-  public var theViewVerticalBackports: VwrCandidateVerticalBackports {
-    .init(
-      controller: self, thePool: thePoolVertical,
+  private var theViewVerticalBackports: some View {
+    VwrCandidateVerticalBackports(
+      controller: self, thePool: Self.thePoolVertical,
       tooltip: tooltip, reverseLookupResult: reverseLookupResult
-    )
+    ).edgesIgnoringSafeArea(.top)
   }
 
-  public var thePool: CandidatePool {
+  private var thePool: CandidatePool {
     get {
       switch currentLayout {
-        case .horizontal: return thePoolHorizontal
-        case .vertical: return thePoolVertical
+        case .horizontal: return Self.thePoolHorizontal
+        case .vertical: return Self.thePoolVertical
         @unknown default: return .init(candidates: [], rowCapacity: 0)
       }
     }
     set {
       switch currentLayout {
-        case .horizontal: thePoolHorizontal = newValue
-        case .vertical: thePoolVertical = newValue
+        case .horizontal: Self.thePoolHorizontal = newValue
+        case .vertical: Self.thePoolVertical = newValue
         @unknown default: break
       }
     }
@@ -81,7 +83,6 @@ public class CtlCandidateTDK: CtlCandidate {
     super.init(layout)
     window = panel
     currentLayout = layout
-    reloadData()
   }
 
   @available(*, unavailable)
@@ -98,17 +99,17 @@ public class CtlCandidateTDK: CtlCandidate {
 
     switch currentLayout {
       case .horizontal:
-        thePoolHorizontal = .init(
+        Self.thePoolHorizontal = .init(
           candidates: delegate.candidatePairs(conv: true).map(\.1), rowCapacity: 6,
           rows: maxLinesPerPage, selectionKeys: delegate.selectionKeys, locale: locale
         )
-        thePoolHorizontal.highlight(at: 0)
+        Self.thePoolHorizontal.highlight(at: 0)
       case .vertical:
-        thePoolVertical = .init(
+        Self.thePoolVertical = .init(
           candidates: delegate.candidatePairs(conv: true).map(\.1), columnCapacity: 6,
           columns: maxLinesPerPage, selectionKeys: delegate.selectionKeys, locale: locale
         )
-        thePoolVertical.highlight(at: 0)
+        Self.thePoolVertical.highlight(at: 0)
       @unknown default:
         return
     }
@@ -122,30 +123,24 @@ public class CtlCandidateTDK: CtlCandidate {
       case .horizontal:
         DispatchQueue.main.async { [self] in
           if #available(macOS 12, *) {
-            let newView = NSHostingView(rootView: theViewHorizontal.edgesIgnoringSafeArea(.top))
-            let newSize = newView.fittingSize
-            window.contentView = newView
-            window.setContentSize(newSize)
+            Self.currentView = NSHostingView(rootView: theViewHorizontal)
           } else {
-            let newView = NSHostingView(rootView: theViewHorizontalBackports.edgesIgnoringSafeArea(.top))
-            let newSize = newView.fittingSize
-            window.contentView = newView
-            window.setContentSize(newSize)
+            Self.currentView = NSHostingView(rootView: theViewHorizontalBackports)
           }
+          let newSize = Self.currentView.fittingSize
+          window.contentView = Self.currentView
+          window.setContentSize(newSize)
         }
       case .vertical:
         DispatchQueue.main.async { [self] in
           if #available(macOS 12, *) {
-            let newView = NSHostingView(rootView: theViewVertical.edgesIgnoringSafeArea(.top))
-            let newSize = newView.fittingSize
-            window.contentView = newView
-            window.setContentSize(newSize)
+            Self.currentView = NSHostingView(rootView: theViewVertical)
           } else {
-            let newView = NSHostingView(rootView: theViewVerticalBackports.edgesIgnoringSafeArea(.top))
-            let newSize = newView.fittingSize
-            window.contentView = newView
-            window.setContentSize(newSize)
+            Self.currentView = NSHostingView(rootView: theViewVerticalBackports)
           }
+          let newSize = Self.currentView.fittingSize
+          window.contentView = Self.currentView
+          window.setContentSize(newSize)
         }
       @unknown default:
         return
diff --git a/Packages/vChewing_CandidateWindow/Sources/CandidateWindow/TDKCandidates/VwrCandidateTDK/VwrCandidateHorizontal.swift b/Packages/vChewing_CandidateWindow/Sources/CandidateWindow/TDKCandidates/VwrCandidateTDK/VwrCandidateHorizontal.swift
index c9cb1df9..8c0882ab 100644
--- a/Packages/vChewing_CandidateWindow/Sources/CandidateWindow/TDKCandidates/VwrCandidateTDK/VwrCandidateHorizontal.swift
+++ b/Packages/vChewing_CandidateWindow/Sources/CandidateWindow/TDKCandidates/VwrCandidateTDK/VwrCandidateHorizontal.swift
@@ -22,20 +22,20 @@ struct CandidatePoolViewUIHorizontal_Previews: PreviewProvider {
     "吹", "大", "地", "草", "枝", "擺",
   ]
   static var thePool: CandidatePool {
-    let result = CandidatePool(candidates: testCandidates, rowCapacity: 6)
+    var result = CandidatePool(candidates: testCandidates, rowCapacity: 6)
     // 下一行待解決：無論這裡怎麼指定高亮選中項是哪一筆，其所在行都得被卷動到使用者眼前。
     result.highlight(at: 5)
     return result
   }
 
   static var previews: some View {
-    VwrCandidateHorizontal(controller: .init(.horizontal), thePool: thePool).fixedSize()
+    VwrCandidateHorizontal(controller: nil, thePool: thePool).fixedSize()
   }
 }
 
 @available(macOS 12, *)
 public struct VwrCandidateHorizontal: View {
-  public var controller: CtlCandidateTDK
+  public weak var controller: CtlCandidateTDK?
   @Environment(\.colorScheme) var colorScheme
   @State public var thePool: CandidatePool
   @State public var tooltip: String = ""
@@ -46,7 +46,7 @@ public struct VwrCandidateHorizontal: View {
   }
 
   private func didSelectCandidateAt(_ pos: Int) {
-    if let delegate = controller.delegate {
+    if let delegate = controller?.delegate {
       delegate.candidatePairSelected(at: pos)
     }
   }
@@ -93,7 +93,7 @@ public struct VwrCandidateHorizontal: View {
       }
       .fixedSize(horizontal: false, vertical: true)
       .padding([.horizontal], 5).padding([.top], 5).padding([.bottom], -1)
-      if controller.delegate?.showReverseLookupResult ?? true {
+      if controller?.delegate?.showReverseLookupResult ?? true {
         ZStack(alignment: .leading) {
           Color(white: colorScheme == .dark ? 0.15 : 0.97)
           HStack(alignment: .center, spacing: 4) {
diff --git a/Packages/vChewing_CandidateWindow/Sources/CandidateWindow/TDKCandidates/VwrCandidateTDK/VwrCandidateVertical.swift b/Packages/vChewing_CandidateWindow/Sources/CandidateWindow/TDKCandidates/VwrCandidateTDK/VwrCandidateVertical.swift
index 119ce4e9..efbdf792 100644
--- a/Packages/vChewing_CandidateWindow/Sources/CandidateWindow/TDKCandidates/VwrCandidateTDK/VwrCandidateVertical.swift
+++ b/Packages/vChewing_CandidateWindow/Sources/CandidateWindow/TDKCandidates/VwrCandidateTDK/VwrCandidateVertical.swift
@@ -21,20 +21,20 @@ struct CandidatePoolViewUIVertical_Previews: PreviewProvider {
     "吹", "大", "地", "草", "枝", "擺",
   ]
   static var thePool: CandidatePool {
-    let result = CandidatePool(candidates: testCandidates, columnCapacity: 6, selectionKeys: "123456789")
+    var result = CandidatePool(candidates: testCandidates, columnCapacity: 6, selectionKeys: "123456789")
     // 下一行待解決：無論這裡怎麼指定高亮選中項是哪一筆，其所在行都得被卷動到使用者眼前。
     result.highlight(at: 5)
     return result
   }
 
   static var previews: some View {
-    VwrCandidateVertical(controller: .init(.horizontal), thePool: thePool).fixedSize()
+    VwrCandidateVertical(controller: nil, thePool: thePool).fixedSize()
   }
 }
 
 @available(macOS 12, *)
 public struct VwrCandidateVertical: View {
-  public var controller: CtlCandidateTDK
+  public weak var controller: CtlCandidateTDK?
   @Environment(\.colorScheme) var colorScheme
   @State public var thePool: CandidatePool
   @State public var tooltip: String = ""
@@ -45,7 +45,7 @@ public struct VwrCandidateVertical: View {
   }
 
   private func didSelectCandidateAt(_ pos: Int) {
-    if let delegate = controller.delegate {
+    if let delegate = controller?.delegate {
       delegate.candidatePairSelected(at: pos)
     }
   }
@@ -100,7 +100,7 @@ public struct VwrCandidateVertical: View {
         }
       }
       .fixedSize(horizontal: true, vertical: false).padding(5)
-      if controller.delegate?.showReverseLookupResult ?? true {
+      if controller?.delegate?.showReverseLookupResult ?? true {
         ZStack(alignment: .leading) {
           Color(white: colorScheme == .dark ? 0.15 : 0.97)
           HStack(alignment: .center, spacing: 4) {
diff --git a/Packages/vChewing_CandidateWindow/Sources/CandidateWindow/TDKCandidates/VwrCandidateTDK_Backports/VwrCandidateHorizontalBackports.swift b/Packages/vChewing_CandidateWindow/Sources/CandidateWindow/TDKCandidates/VwrCandidateTDK_Backports/VwrCandidateHorizontalBackports.swift
index c1c16c31..b8029593 100644
--- a/Packages/vChewing_CandidateWindow/Sources/CandidateWindow/TDKCandidates/VwrCandidateTDK_Backports/VwrCandidateHorizontalBackports.swift
+++ b/Packages/vChewing_CandidateWindow/Sources/CandidateWindow/TDKCandidates/VwrCandidateTDK_Backports/VwrCandidateHorizontalBackports.swift
@@ -23,20 +23,20 @@ struct CandidatePoolViewUIHorizontalBackports_Previews: PreviewProvider {
     "吹", "大", "地", "草", "枝", "擺",
   ]
   static var thePool: CandidatePool {
-    let result = CandidatePool(candidates: testCandidates, rowCapacity: 6)
+    var result = CandidatePool(candidates: testCandidates, rowCapacity: 6)
     // 下一行待解決：無論這裡怎麼指定高亮選中項是哪一筆，其所在行都得被卷動到使用者眼前。
     result.highlight(at: 5)
     return result
   }
 
   static var previews: some View {
-    VwrCandidateHorizontalBackports(controller: .init(.horizontal), thePool: thePool).fixedSize()
+    VwrCandidateHorizontalBackports(controller: nil, thePool: thePool).fixedSize()
   }
 }
 
 @available(macOS 10.15, *)
 public struct VwrCandidateHorizontalBackports: View {
-  public var controller: CtlCandidateTDK
+  public weak var controller: CtlCandidateTDK?
   @Environment(\.colorScheme) var colorScheme
   @State public var thePool: CandidatePool
   @State public var tooltip: String = ""
@@ -47,7 +47,7 @@ public struct VwrCandidateHorizontalBackports: View {
   }
 
   private func didSelectCandidateAt(_ pos: Int) {
-    if let delegate = controller.delegate {
+    if let delegate = controller?.delegate {
       delegate.candidatePairSelected(at: pos)
     }
   }
@@ -94,7 +94,7 @@ public struct VwrCandidateHorizontalBackports: View {
       }
       .fixedSize(horizontal: false, vertical: true)
       .padding([.horizontal], 5).padding([.top], 5).padding([.bottom], -1)
-      if controller.delegate?.showReverseLookupResult ?? true {
+      if controller?.delegate?.showReverseLookupResult ?? true {
         ZStack(alignment: .leading) {
           Color(white: colorScheme == .dark ? 0.15 : 0.97)
           HStack(alignment: .center, spacing: 4) {
@@ -116,7 +116,7 @@ public struct VwrCandidateHorizontalBackports: View {
           Color(white: colorScheme == .dark ? 0.2 : 0.9)
         } else {
           Color(white: colorScheme == .dark ? 0.0 : 1)
-          controller.highlightedColorUIBackports
+          controller?.highlightedColorUIBackports
         }
         HStack(alignment: .center) {
           if !tooltip.isEmpty {
diff --git a/Packages/vChewing_CandidateWindow/Sources/CandidateWindow/TDKCandidates/VwrCandidateTDK_Backports/VwrCandidateVerticalBackports.swift b/Packages/vChewing_CandidateWindow/Sources/CandidateWindow/TDKCandidates/VwrCandidateTDK_Backports/VwrCandidateVerticalBackports.swift
index 71051b82..5c6f1643 100644
--- a/Packages/vChewing_CandidateWindow/Sources/CandidateWindow/TDKCandidates/VwrCandidateTDK_Backports/VwrCandidateVerticalBackports.swift
+++ b/Packages/vChewing_CandidateWindow/Sources/CandidateWindow/TDKCandidates/VwrCandidateTDK_Backports/VwrCandidateVerticalBackports.swift
@@ -22,20 +22,20 @@ struct CandidatePoolViewUIVerticalBackports_Previews: PreviewProvider {
     "吹", "大", "地", "草", "枝", "擺",
   ]
   static var thePool: CandidatePool {
-    let result = CandidatePool(candidates: testCandidates, columnCapacity: 6, selectionKeys: "123456789")
+    var result = CandidatePool(candidates: testCandidates, columnCapacity: 6, selectionKeys: "123456789")
     // 下一行待解決：無論這裡怎麼指定高亮選中項是哪一筆，其所在行都得被卷動到使用者眼前。
     result.highlight(at: 5)
     return result
   }
 
   static var previews: some View {
-    VwrCandidateVerticalBackports(controller: .init(.horizontal), thePool: thePool).fixedSize()
+    VwrCandidateVerticalBackports(controller: nil, thePool: thePool).fixedSize()
   }
 }
 
 @available(macOS 10.15, *)
 public struct VwrCandidateVerticalBackports: View {
-  public var controller: CtlCandidateTDK
+  public weak var controller: CtlCandidateTDK?
   @Environment(\.colorScheme) var colorScheme
   @State public var thePool: CandidatePool
   @State public var tooltip: String = ""
@@ -46,7 +46,7 @@ public struct VwrCandidateVerticalBackports: View {
   }
 
   private func didSelectCandidateAt(_ pos: Int) {
-    if let delegate = controller.delegate {
+    if let delegate = controller?.delegate {
       delegate.candidatePairSelected(at: pos)
     }
   }
@@ -101,7 +101,7 @@ public struct VwrCandidateVerticalBackports: View {
         }
       }
       .fixedSize(horizontal: true, vertical: false).padding(5)
-      if controller.delegate?.showReverseLookupResult ?? true {
+      if controller?.delegate?.showReverseLookupResult ?? true {
         ZStack(alignment: .leading) {
           Color(white: colorScheme == .dark ? 0.15 : 0.97)
           HStack(alignment: .center, spacing: 4) {
@@ -123,7 +123,7 @@ public struct VwrCandidateVerticalBackports: View {
           Color(white: colorScheme == .dark ? 0.2 : 0.9)
         } else {
           Color(white: colorScheme == .dark ? 0.0 : 1)
-          controller.highlightedColorUIBackports
+          controller?.highlightedColorUIBackports
         }
         HStack(alignment: .center) {
           if !tooltip.isEmpty {