Gestures: flick, long-press alternates, trackpad, layer slide, rollover

- PointerTracker: per-finger gesture state machine (pure, unit-tested)
- AlternatesPicker + AlternatesPopup.qml: long-press choices, finger selects
- Space long-press trackpad moves the cursor with arrow keysyms
- Slide from .?123 onto a symbol types it and switches back
- New finger commits pending taps (iOS rollover)
- Flick animation: secondary symbol slides down as the finger moves
- Transparent popup margin with an input region that passes clicks through
- tst_keyboardsurface: end-to-end gesture tests on the real QML

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

qml/AlternatesPopup.qml

@@ -0,0 +1,54 @@
+import QtQuick
+import Sloposk
+
+// Long-press choices above a key; the one under the finger is highlighted.
+Item {
+    id: popup
+
+    required property AlternatesPicker picker
+
+    visible: picker.open
+    x: picker.rect.x
+    y: picker.rect.y
+    width: picker.rect.width
+    height: picker.rect.height
+
+    Rectangle {
+        anchors { fill: background; topMargin: 1; bottomMargin: -2 }
+        radius: background.radius
+        color: Theme.keyShadow
+    }
+
+    Rectangle {
+        id: background
+        anchors.fill: parent
+        radius: Theme.keyRadius + 2
+        color: Theme.characterKey
+    }
+
+    Row {
+        anchors.fill: parent
+
+        Repeater {
+            model: popup.picker.choices
+
+            delegate: Rectangle {
+                required property string modelData
+                required property int index
+                readonly property bool selected: index === popup.picker.selected
+
+                width: popup.width / popup.picker.choices.length
+                height: popup.height
+                radius: Theme.keyRadius
+                color: selected ? Theme.accent : "transparent"
+
+                Text {
+                    anchors.centerIn: parent
+                    text: parent.modelData
+                    font.pixelSize: parent.height * 0.4
+                    color: parent.selected ? Theme.accentText : Theme.text
+                }
+            }
+        }
+    }
+}

qml/Key.qml

@@ -13,7 +13,9 @@ Item {
     required property real keyWidth
     required property real keyHeight
     required property bool pressed
+    required property real flickProgress
     property int shiftMode: KeyboardController.Off
+    property bool blank: false // labels hidden, e.g. in trackpad mode
 
     readonly property bool isCharacter: keyType === "char" || keyType === "space"
     readonly property bool shiftActive: keyType === "shift" && shiftMode !== KeyboardController.Off
@@ -52,13 +54,18 @@ Item {
         color: key.lit ? Theme.characterKey : Theme.functionKey
     }
 
+    // Flicking slides the secondary symbol down into the main position.
     Text {
         id: flick
-        visible: text !== ""
+        readonly property real restY: key.height * 0.1
+        readonly property real centerY: (key.height - height) / 2
+
+        visible: text !== "" && !key.blank
         text: key.flickLabel
-        anchors { horizontalCenter: parent.horizontalCenter; top: parent.top; topMargin: key.height * 0.1 }
-        font.pixelSize: key.height * 0.24
-        color: Theme.secondaryText
+        anchors.horizontalCenter: parent.horizontalCenter
+        y: restY + (centerY - restY) * key.flickProgress
+        font.pixelSize: key.height * (0.24 + 0.16 * key.flickProgress)
+        color: key.flickProgress >= 1 ? Theme.text : Theme.secondaryText
     }
 
     Text {
@@ -70,5 +77,7 @@ Item {
         }
         font.pixelSize: key.height * (key.isWord ? 0.24 : flick.visible ? 0.34 : 0.4)
         color: Theme.text
+        visible: !key.blank
+        opacity: 1 - key.flickProgress
     }
 }

qml/Keyboard.qml

@@ -8,6 +8,12 @@ KeyboardSurface {
         model: surface.model
         delegate: Key {
             shiftMode: surface.controller ? surface.controller.shiftMode : KeyboardController.Off
+            blank: surface.trackpadActive
         }
     }
+
+    AlternatesPopup {
+        picker: surface.alternates
+        z: 1
+    }
 }

qml/Main.qml

@@ -8,17 +8,29 @@ Window {
     required property KeyboardController controller
     property var placement: null // FloatingWindow, set from C++
 
+    // Transparent room above the keyboard for long-press popups on the top row.
+    readonly property real popupMargin: 90
+    // Outside this, input passes through to whatever is below the window.
+    readonly property rect inputRegion: keyboard.alternates.open
+        ? Qt.rect(0, 0, width, height)
+        : Qt.rect(panel.x, panel.y, panel.width, panel.height)
+
     width: 1000
-    height: 340
+    height: 340 + popupMargin
     visible: false
     color: "transparent"
 
+    onInputRegionChanged: placement?.setInputRegion(inputRegion)
+    onPlacementChanged: placement?.setInputRegion(inputRegion)
+
     Rectangle {
-        anchors.fill: parent
+        id: panel
+        anchors { fill: parent; topMargin: root.popupMargin }
         radius: Theme.windowRadius
         color: Theme.background
 
         Keyboard {
+            id: keyboard
             anchors { left: parent.left; right: parent.right; top: parent.top; bottom: handle.top }
             anchors.margins: 2
             model: root.layoutModel

qml/Theme.qml

@@ -13,6 +13,8 @@ QtObject {
     readonly property color text: dark ? "#ffffff" : "#000000"
     readonly property color secondaryText: dark ? "#a5a5aa" : "#8a8a8e"
     readonly property color handle: dark ? "#8e8e93" : "#7c7c80"
+    readonly property color accent: dark ? "#0a84ff" : "#007aff"
+    readonly property color accentText: "#ffffff"
 
     readonly property real windowRadius: 14
     readonly property real keyRadius: 6