Remap bar and background surfaces when their monitor moves

Hyprland leaves an already-mapped layer surface at its old global
position when its monitor moves within the layout: undocking disables
the internal panel, the external monitor shifts to x=0, and the bar and
background keep rendering at the old offset until unmapped and remapped.
Watch each screen's origin and briefly unmap the window when it moves so
the compositor re-places the surface at the monitor's new origin.

Co-Authored-By: Claude Fable 5 <noreply@anthropic.com>

shell/Ui/ScreenMoveRemap.qml

@@ -0,0 +1,43 @@
+import QtQuick
+
+// Hyprland leaves an already-mapped layer surface at its old global position
+// when its monitor moves within the layout: undocking disables the internal
+// panel, the external monitor shifts to x=0, and long-lived surfaces such as
+// the bar and background keep rendering at the old offset — or entirely
+// off-screen — until they are unmapped and remapped. Watch the screen's
+// origin and pulse `remapping` when it moves; the owning window folds that
+// into its `visible` binding so the compositor re-places the surface at the
+// monitor's new origin.
+Item {
+  id: root
+
+  required property var window
+  readonly property var screen: window ? window.screen : null
+
+  // Fold into the window's binding: visible: <shown> && !guard.remapping
+  property bool remapping: false
+
+  visible: false
+
+  // A layout reshuffle can move the monitor more than once before it lands.
+  // Let the positions settle before the single remap pulse.
+  Timer {
+    id: settleTimer
+    interval: 200
+    onTriggered: root.remapping = true
+  }
+
+  // Hold the surface unmapped for a beat so the compositor processes the
+  // unmap before the remap instead of coalescing them into a no-op.
+  Timer {
+    interval: 50
+    running: root.remapping
+    onTriggered: root.remapping = false
+  }
+
+  Connections {
+    target: root.screen
+    function onXChanged() { settleTimer.restart() }
+    function onYChanged() { settleTimer.restart() }
+  }
+}

shell/Ui/qmldir

@@ -24,6 +24,7 @@ PanelSeparator 1.0 PanelSeparator.qml
 PanelSlider 1.0 PanelSlider.qml
 PanelToolTip 1.0 PanelToolTip.qml
 PointerMoveGate 1.0 PointerMoveGate.qml
+ScreenMoveRemap 1.0 ScreenMoveRemap.qml
 PopupCard 1.0 PopupCard.qml
 SearchableDropdown 1.0 SearchableDropdown.qml
 TextField 1.0 TextField.qml

shell/plugins/background/Background.qml

@@ -5,6 +5,7 @@ import QtQuick
 import QtQuick.Effects
 import QtQuick.Shapes
 import qs.Commons
+import qs.Ui
 
 Item {
   id: root
@@ -185,8 +186,13 @@ Item {
       required property var modelData
 
       screen: modelData
-      visible: true
+      visible: !remapGuard.remapping
       anchors { top: true; bottom: true; left: true; right: true }
+
+      ScreenMoveRemap {
+        id: remapGuard
+        window: panel
+      }
       color: "transparent"
       // Keep render updates enabled. The background layer has been observed to
       // lose its committed buffer while parked with updatesEnabled=false,

shell/plugins/bar/Bar.qml

@@ -938,7 +938,12 @@ Item {
   component BarPanel: PanelWindow {
     id: barWindow
 
-    visible: !root.barHidden
+    visible: !root.barHidden && !remapGuard.remapping
+
+    ScreenMoveRemap {
+      id: remapGuard
+      window: barWindow
+    }
 
     anchors {
       top: root.position === "top" || root.vertical