Preview task-group selections until Meta is released

plasma-task-group-shortcuts/pendingselection.h

@@ -0,0 +1,26 @@
+// SPDX-License-Identifier: MIT
+
+#pragma once
+
+#include <QAbstractItemModel>
+#include <QPersistentModelIndex>
+
+// A preview is not an activation: only the final selection enters focus history.
+class PendingSelection : public QObject
+{
+    Q_OBJECT
+
+public:
+    explicit PendingSelection(QAbstractItemModel &model);
+    void select(const QModelIndex &task, bool defer);
+    void finish();
+    void cancel();
+
+Q_SIGNALS:
+    void previewRequested(const QModelIndex &task);
+    void previewHidden();
+    void activationRequested(const QModelIndex &task);
+
+private:
+    QPersistentModelIndex m_task;
+};