Track input-method contexts by identity

- deactivate only drops the context it names; one replaced by an activate
  is kept until KWin deactivates it
- Moving focus straight from one field to another ends a manual hide

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>

src/backend/KWinInputMethod.cpp

@@ -14,9 +14,9 @@ void KWinInputMethodGlobal::zwp_input_method_v1_activate(::zwp_input_method_cont
     Q_EMIT activated(context);
 }
 
-void KWinInputMethodGlobal::zwp_input_method_v1_deactivate(::zwp_input_method_context_v1 *)
+void KWinInputMethodGlobal::zwp_input_method_v1_deactivate(::zwp_input_method_context_v1 *context)
 {
-    Q_EMIT deactivated();
+    Q_EMIT deactivated(context);
 }
 
 KWinInputMethod::KWinInputMethod(QObject *parent)
@@ -87,13 +87,20 @@ void KWinInputMethod::setKeyPressed(quint32 keysym, bool pressed)
 
 void KWinInputMethod::activate(::zwp_input_method_context_v1 *context)
 {
+    m_previous = std::move(m_context);
     m_context = std::make_unique<KWinInputContext>(context);
     connect(m_context.get(), &KWinInputContext::contextChanged, this, &TextBackend::contextChanged);
     Q_EMIT activeChanged();
 }
 
-void KWinInputMethod::deactivate()
+void KWinInputMethod::deactivate(::zwp_input_method_context_v1 *context)
 {
+    if (m_previous && m_previous->object() == context) {
+        m_previous.reset();
+        return;
+    }
+    if (!m_context || m_context->object() != context)
+        return;
     m_context.reset();
     Q_EMIT activeChanged();
     Q_EMIT contextChanged();

src/backend/KWinInputMethod.h

@@ -22,7 +22,7 @@ public:
 
 Q_SIGNALS:
     void activated(::zwp_input_method_context_v1 *context);
-    void deactivated();
+    void deactivated(::zwp_input_method_context_v1 *context);
 
 protected:
     void zwp_input_method_v1_activate(::zwp_input_method_context_v1 *context) override;
@@ -57,9 +57,11 @@ Q_SIGNALS:
 
 private:
     void activate(::zwp_input_method_context_v1 *context);
-    void deactivate();
+    void deactivate(::zwp_input_method_context_v1 *context);
 
     KWinInputMethodGlobal m_global;
     KWinFakeInput m_fakeInput;
     std::unique_ptr<KWinInputContext> m_context;
+    // Replaced by an activate before KWin deactivated it; kept until it does.
+    std::unique_ptr<KWinInputContext> m_previous;
 };

src/backend/TextBackend.h

@@ -34,6 +34,7 @@ public:
     virtual void setKeyPressed(quint32 keysym, bool pressed) = 0;
 
 Q_SIGNALS:
+    // Also when focus moves straight from one field to another.
     void activeChanged();
     void contextChanged();
 };

src/window/VisibilityController.cpp

@@ -2,8 +2,6 @@
 
 void VisibilityController::setFieldActive(bool active)
 {
-    if (active == m_fieldActive)
-        return;
     m_fieldActive = active;
     m_override.reset();
     update();

src/window/VisibilityController.h

@@ -7,7 +7,8 @@
 //  - while a text field is focused
 //  - always, if the user wants it (to type into any window) or when running
 //    standalone (no input-method connection)
-//  - show()/hide()/toggle() override that until the focus changes
+//  - show()/hide()/toggle() override that until the focus changes, also
+//    from one field straight to another
 class VisibilityController : public QObject
 {
     Q_OBJECT
@@ -17,6 +18,7 @@ public:
 
     bool isVisible() const { return m_visible; }
 
+    // Called on every focus change, even when a field follows a field.
     void setFieldActive(bool active);
     void setStandalone(bool standalone);
     void setAlwaysVisible(bool always);