Add Hotkey type for defining and displaying shortcuts

Hotkey.qml

@@ -0,0 +1,30 @@
+// SPDX-License-Identifier: Unlicense
+
+import QtQuick 2.12
+import QtQuick.Controls 2.13
+
+// Define and display a shortcut to focus the given control.
+Label {
+    required property Item control
+    property alias sequence: shortcut.sequence
+
+    text: shortcut.nativeText
+    visible: !control.activeFocus
+
+    color: 'gray'
+    padding: 1
+    leftPadding: 2*padding
+    rightPadding: 2*padding
+
+    background: Rectangle {
+        color: palette.base
+        border { color: Qt.lighter(parent.color); width: 1 }
+        opacity: 0.9
+        radius: 2
+    }
+
+    Shortcut {
+        id: shortcut
+        onActivated: control.forceActiveFocus()
+    }
+}