qml: introduce InfoBanner allowing a clickable sticky message to stay below header and

implement ln utxo reserve check with warning. Clicking shows a suggestion to swap.

electrum/gui/qml/components/WalletMainView.qml

@@ -447,6 +447,7 @@ Item {
     Connections {
         target: Daemon
         function onWalletLoaded() {
+            infobanner.hide() // start hidden when switching wallets
             if (_intentUri) {
                 invoiceParser.recipient = _intentUri
                 _intentUri = ''
@@ -497,6 +498,27 @@ Item {
             })
             dialog.open()
         }
+        function onBalanceChanged() {
+            // ln low reserve warning
+            if (Daemon.currentWallet.isLowReserve) {
+                var message = [
+                    qsTr('You do not have enough on-chain funds to protect your Lightning channels.'),
+                    qsTr('You should have at least %1 on-chain in order to be able to sweep channel outputs.').arg(Config.formatSats(Config.lnUtxoReserve) + ' ' + Config.baseUnit)
+                ].join(' ')
+                infobanner.show(message, function() {
+                    var dialog = app.messageDialog.createObject(app, {
+                        text: message + '\n\n' + qsTr('Do you want to perform a swap?'),
+                        yesno: true
+                    })
+                    dialog.accepted.connect(function() {
+                        app.startSwap()
+                    })
+                    dialog.open()
+                })
+            } else {
+                infobanner.hide()
+            }
+        }
     }
 
     Component {

electrum/gui/qml/components/controls/InfoBanner.qml

@@ -0,0 +1,124 @@
+import QtQuick
+import QtQuick.Layouts
+import QtQuick.Controls
+import QtQuick.Controls.Material
+import QtQuick.Controls.Material.impl
+
+Item {
+    id: root
+
+    property string message
+    property bool autohide: false
+    property color color: constants.colorAlpha(constants.colorWarning, 0.1)
+    property url icon: Qt.resolvedUrl('../../../icons/warning.png')
+    property alias font: messageLabel.font
+
+    property bool _hide: true
+    property var _clicked_fn
+
+    clip:true
+    z: 1
+    layer.enabled: height > 0
+    layer.effect: ElevationEffect {
+        elevation: constants.paddingXLarge
+        fullWidth: true
+    }
+
+    state: 'hidden'
+
+    states: [
+        State {
+            name: 'hidden'; when: _hide
+            PropertyChanges { target: root; implicitHeight: 0 }
+        },
+        State {
+            name: 'expanded'; when: !_hide
+            PropertyChanges { target: root; implicitHeight: layout.implicitHeight }
+        }
+    ]
+
+    transitions: [
+        Transition {
+            from: 'hidden'; to: 'expanded'
+            SequentialAnimation {
+                PropertyAction  { target: root; property: 'visible'; value: true }
+                NumberAnimation { target: root; properties: 'implicitHeight'; duration: 300; easing.type: Easing.OutQuad }
+            }
+        },
+        Transition {
+            from: 'expanded'; to: 'hidden'
+            SequentialAnimation {
+                NumberAnimation { target: root; properties: 'implicitHeight'; duration: 100; easing.type: Easing.OutQuad }
+                PropertyAction  { target: root; property: 'visible'; value: false }
+            }
+        }
+    ]
+
+    function show(message, on_clicked=undefined) {
+        root.message = message
+        root._clicked_fn = on_clicked
+        root._hide = false
+        if (autohide)
+            closetimer.start()
+    }
+
+    function hide() {
+        closetimer.stop()
+        root._hide = true
+    }
+
+    Rectangle {
+        id: rect
+        width: root.width
+        height: layout.height
+        color: root.color
+        anchors.bottom: root.bottom
+
+        ColumnLayout {
+            id: layout
+            width: parent.width
+            spacing: 0
+
+            RowLayout {
+                Layout.margins: constants.paddingLarge
+                spacing: constants.paddingSmall
+
+                Image {
+                    source: root.icon
+                    Layout.preferredWidth: constants.iconSizeLarge
+                    Layout.preferredHeight: constants.iconSizeLarge
+                }
+
+                Label {
+                    id: messageLabel
+                    Layout.fillWidth: true
+                    font.pixelSize: constants.fontSizeSmall
+                    color: Material.foreground
+                    wrapMode: Text.Wrap
+                    text: root.message
+                }
+            }
+            Rectangle {
+                Layout.preferredHeight: 2
+                Layout.fillWidth: true
+                color: Material.accentColor
+            }
+        }
+    }
+
+    MouseArea {
+        anchors.fill: parent
+        onClicked: {
+            if (root._clicked_fn)
+                root._clicked_fn()
+        }
+    }
+
+    Timer {
+        id: closetimer
+        interval: 5000
+        repeat: false
+        onTriggered: _hide = true
+    }
+
+}

electrum/gui/qml/components/main.qml

@@ -33,6 +33,7 @@ ApplicationWindow
 
     property alias stack: mainStackView
     property alias keyboardFreeZone: _keyboardFreeZone
+    property alias infobanner: _infobanner
 
     property variant activeDialogs: []
 
@@ -244,22 +245,34 @@ ApplicationWindow
         }
     }
 
-    StackView {
-        id: mainStackView
+    ColumnLayout {
         width: parent.width
         height: _keyboardFreeZone.height - header.height
-        initialItem: Component {
-            WalletMainView {}
+        spacing: 0
+
+        InfoBanner {
+            id: _infobanner
+            Layout.fillWidth: true
         }
 
-        function getRoot() {
-            return mainStackView.get(0)
-        }
-        function pushOnRoot(item) {
-            if (mainStackView.depth > 1) {
-                mainStackView.replace(mainStackView.get(1), item)
-            } else {
-                mainStackView.push(item)
+        StackView {
+            id: mainStackView
+            Layout.fillHeight: true
+            Layout.fillWidth: true
+
+            initialItem: Component {
+                WalletMainView {}
+            }
+
+            function getRoot() {
+                return mainStackView.get(0)
+            }
+            function pushOnRoot(item) {
+                if (mainStackView.depth > 1) {
+                    mainStackView.replace(mainStackView.get(1), item)
+                } else {
+                    mainStackView.push(item)
+                }
             }
         }
     }

electrum/gui/qml/qeconfig.py

@@ -291,6 +291,12 @@ class QEConfig(AuthMixin, QObject):
             self.config.SWAPSERVER_NPUB = swapserver_npub
             self.swapServerNPubChanged.emit()
 
+    lnUtxoReserveChanged = pyqtSignal()
+    @pyqtProperty(QEAmount, notify=lnUtxoReserveChanged)
+    def lnUtxoReserve(self):
+        self._lnutxoreserve = QEAmount(amount_sat=self.config.LN_UTXO_RESERVE)
+        return self._lnutxoreserve
+
     @pyqtSlot('qint64', result=str)
     @pyqtSlot(QEAmount, result=str)
     def formatSatsForEditing(self, satoshis):

electrum/gui/qml/qewallet.py

@@ -513,6 +513,10 @@ class QEWallet(AuthMixin, QObject, QtEventListener):
             self._lightningcanreceive.satsInt = int(self.wallet.lnworker.num_sats_can_receive())
         return self._lightningcanreceive
 
+    @pyqtProperty(bool, notify=balanceChanged)
+    def isLowReserve(self):
+        return self.wallet.is_low_reserve()
+
     @pyqtProperty(QEAmount, notify=dataChanged)
     def minChannelFunding(self):
         return self._minchannelfunding