diff --git a/Source/Modules/ControllerModules/ctlInputMethod_Core.swift b/Source/Modules/ControllerModules/ctlInputMethod_Core.swift
index 231442c5..880c3dc2 100644
--- a/Source/Modules/ControllerModules/ctlInputMethod_Core.swift
+++ b/Source/Modules/ControllerModules/ctlInputMethod_Core.swift
@@ -81,11 +81,12 @@ class ctlInputMethod: IMKInputController {
       keyHandler.composer.clear()
       handle(state: keyHandler.buildInputtingState)
     }
-    if state.hasComposition {
+    let isSecureMode = mgrPrefs.clientsIMKTextInputIncapable.contains(clientBundleIdentifier)
+    if state.hasComposition, !isSecureMode {
       /// 將傳回的新狀態交給調度函式。
       handle(state: IMEState.ofCommitting(textToCommit: state.displayedText))
     }
-    handle(state: IMEState.ofEmpty())
+    handle(state: isSecureMode ? IMEState.ofAbortion() : IMEState.ofEmpty())
   }
 
   // MARK: - IMKInputController 方法
diff --git a/Source/Modules/ControllerModules/ctlInputMethod_HandleDisplay.swift b/Source/Modules/ControllerModules/ctlInputMethod_HandleDisplay.swift
index 7e7d25b2..a3d64931 100644
--- a/Source/Modules/ControllerModules/ctlInputMethod_HandleDisplay.swift
+++ b/Source/Modules/ControllerModules/ctlInputMethod_HandleDisplay.swift
@@ -13,6 +13,15 @@ import Cocoa
 // MARK: - Tooltip Display and Candidate Display Methods
 
 extension ctlInputMethod {
+  // 有些 App 會濫用內文組字區的內容來預測使用者的輸入行為。
+  // 對此類 App 有疑慮者，可以將這類 App 登記到客體管理員當中。
+  // 這樣，不但強制使用（限制讀音 20 個的）浮動組字窗，而且內文組字區只會顯示一個空格。
+  var attributedStringSecured: (NSAttributedString, NSRange) {
+    mgrPrefs.clientsIMKTextInputIncapable.contains(clientBundleIdentifier)
+      ? (state.data.attributedStringPlaceholder, NSRange(location: 0, length: 0))
+      : (state.attributedString, NSRange(state.data.u16MarkedRange))
+  }
+
   func lineHeightRect(zeroCursor: Bool = false) -> NSRect {
     var lineHeightRect = NSRect.seniorTheBeast
     guard let client = client() else {
diff --git a/Source/Modules/ControllerModules/ctlInputMethod_HandleStates.swift b/Source/Modules/ControllerModules/ctlInputMethod_HandleStates.swift
index 12423441..410ce31f 100644
--- a/Source/Modules/ControllerModules/ctlInputMethod_HandleStates.swift
+++ b/Source/Modules/ControllerModules/ctlInputMethod_HandleStates.swift
@@ -96,7 +96,7 @@ extension ctlInputMethod {
     guard let client = client() else { return }
     if state.type == .ofAssociates {
       client.setMarkedText(
-        state.attributedString, selectionRange: NSRange(location: 0, length: 0),
+        state.data.attributedStringPlaceholder, selectionRange: NSRange(location: 0, length: 0),
         replacementRange: NSRange(location: NSNotFound, length: NSNotFound)
       )
       return
@@ -107,7 +107,7 @@ extension ctlInputMethod {
       /// 是 0 且取代範圍（replacementRange）為「NSNotFound」罷了。
       /// 也就是說，內文組字區該在哪裡出現，得由客體軟體來作主。
       client.setMarkedText(
-        state.attributedString, selectionRange: NSRange(state.data.u16MarkedRange),
+        attributedStringSecured.0, selectionRange: attributedStringSecured.1,
         replacementRange: NSRange(location: NSNotFound, length: NSNotFound)
       )
       return