qml: show channel backup and explanatory message before local force close, and let user confirm before doing the close operation

also show message dialog after close succeeded instead of just closing the channel close dialog

electrum/gui/qml/components/CloseChannelDialog.qml

@@ -19,6 +19,7 @@ ElDialog {
     iconSource: Qt.resolvedUrl('../../icons/lightning_disconnected.png')
 
     property bool _closing: false
+    property string _closing_method
 
     closePolicy: Popup.NoAutoClose
 
@@ -163,12 +164,50 @@ ElDialog {
             icon.source: '../../icons/closebutton.png'
             enabled: !_closing
             onClicked: {
-                _closing = true
-                channeldetails.closeChannel(closetypegroup.checkedButton.closetype)
+                if (closetypegroup.checkedButton.closetype == 'local_force') {
+                    showBackupThenConfirmClose()
+                } else {
+                    doCloseChannel()
+                }
             }
-
         }
+    }
 
+    function showBackupThenConfirmClose() {
+        var sharedialog = app.genericShareDialog.createObject(app, {
+            title: qsTr('Save channel backup and force close'),
+            text_qr: channeldetails.channelBackup(),
+            text_help: channeldetails.messageForceCloseBackup,
+            helpTextIconStyle: InfoTextArea.IconStyle.Warn
+        })
+        sharedialog.closed.connect(function() {
+            confirmCloseChannel()
+        })
+        sharedialog.open()
+    }
+
+    function confirmCloseChannel() {
+        var confirmdialog = app.messageDialog.createObject(app, {
+            title: qsTr('Confirm force close?'),
+            yesno: true
+        })
+        confirmdialog.accepted.connect(function() {
+            doCloseChannel()
+        })
+        confirmdialog.open()
+    }
+
+    function doCloseChannel() {
+        _closing = true
+        _closing_method = closetypegroup.checkedButton.closetype
+        channeldetails.closeChannel(_closing_method)
+    }
+
+    function showCloseMessage(text) {
+        var msgdialog = app.messageDialog.createObject(app, {
+            text: text
+        })
+        msgdialog.open()
     }
 
     ChannelDetails {
@@ -176,7 +215,10 @@ ElDialog {
         wallet: Daemon.currentWallet
         channelid: dialog.channelid
 
-        onChannelChanged : {
+        onChannelChanged: {
+            if (!channeldetails.canClose)
+                return
+
             // init default choice
             if (channeldetails.canCoopClose)
                 closetypeCoop.checked = true
@@ -186,6 +228,13 @@ ElDialog {
 
         onChannelCloseSuccess: {
             _closing = false
+            if (_closing_method == 'local_force') {
+                showCloseMessage(qsTr('Channel closed. You may need to wait at least %1 blocks, because of CSV delays').arg(channeldetails.toSelfDelay))
+            } else if (_closing_method == 'remote_force') {
+                showCloseMessage(qsTr('Request sent'))
+            } else if (_closing_method == 'cooperative') {
+                showCloseMessage(qsTr('Channel closed'))
+            }
             dialog.close()
         }
 

electrum/gui/qml/components/GenericShareDialog.qml

@@ -12,6 +12,7 @@ ElDialog {
     property string text_qr
     // if text_qr is undefined text will be used
     property string text_help
+    property int helpTextIconStyle: InfoTextArea.IconStyle.Info
 
     title: ''
 
@@ -65,6 +66,7 @@ ElDialog {
                 InfoTextArea {
                     Layout.leftMargin: constants.paddingMedium
                     Layout.rightMargin: constants.paddingMedium
+                    iconStyle: helpTextIconStyle
                     visible: dialog.text_help
                     text: dialog.text_help
                     Layout.fillWidth: true

electrum/gui/qml/qechanneldetails.py

@@ -13,6 +13,7 @@ from .qewallet import QEWallet
 from .qetypes import QEAmount
 from .util import QtEventListener, qt_event_listener, event_listener
 
+
 class QEChannelDetails(QObject, QtEventListener):
     _logger = get_logger(__name__)
 
@@ -171,13 +172,26 @@ class QEChannelDetails(QObject, QtEventListener):
         return self._channel.can_be_deleted()
 
     @pyqtProperty(str, notify=channelChanged)
-    def messageForceClose(self, notify=channelChanged):
+    def messageForceClose(self):
         return messages.MSG_REQUEST_FORCE_CLOSE.strip()
 
+    @pyqtProperty(str, notify=channelChanged)
+    def messageForceCloseBackup(self):
+        return ' '.join([
+            _('If you force-close this channel, the funds you have in it will not be available for {} blocks.').format(self.toSelfDelay),
+            _('During that time, funds will not be recoverable from your seed, and may be lost if you lose your device.'),
+            _('To prevent that, please save this channel backup.'),
+            _('It may be imported in another wallet with the same seed.')
+        ])
+
     @pyqtProperty(bool, notify=channelChanged)
     def isBackup(self):
         return self._channel.is_backup()
 
+    @pyqtProperty(int, notify=channelChanged)
+    def toSelfDelay(self):
+        return self._channel.config[REMOTE].to_self_delay
+
     @pyqtSlot()
     def freezeForSending(self):
         lnworker = self._channel.lnworker