qml: allow manual editing of fee/feerate also improve warning box styling consistency across finalizers, add CPFP new feerate > old feerate check, add relayfee checks for CPFP, DSCancel, proper warning string for no dynamic fee estimates

diff --git a/electrum/fee_policy.py b/electrum/fee_policy.py
index 28c5db8..b00f476 100644
--- a/electrum/fee_policy.py
+++ b/electrum/fee_policy.py
@@ -64,9 +64,10 @@ class FeeMethod(IntEnum):
 
     def name_for_GUI(self):
         names = {
+            FeeMethod.FIXED: _('FIXED'),
             FeeMethod.FEERATE: _('Feerate'),
-            FeeMethod.ETA:_('ETA'),
-            FeeMethod.MEMPOOL :_('Mempool')
+            FeeMethod.ETA: _('ETA'),
+            FeeMethod.MEMPOOL: _('Mempool')
         }
         return names[self]
 
@@ -173,6 +174,8 @@ class FeePolicy(Logger):
         elif self.method == FeeMethod.FEERATE:
             fee_per_byte = self.value/1000
             return format_fee_satoshis(fee_per_byte) + f" {util.UI_UNIT_NAME_FEERATE_SAT_PER_VBYTE}"
+        elif self.method == FeeMethod.FIXED:
+            return f'{self.value} {util.UI_UNIT_NAME_FIXED_SAT}'
 
     def get_estimate_text(self, network: 'Network') -> str:
         """
@@ -233,6 +236,8 @@ class FeePolicy(Logger):
                 fee_rate = network.fee_estimates.eta_to_fee(self.get_slider_pos())
             else:
                 fee_rate = None
+        elif self.method == FeeMethod.FIXED:
+            fee_rate = None
         else:
             raise Exception(self.method)
         if fee_rate is not None:
diff --git a/electrum/gui/messages.py b/electrum/gui/messages.py
index fc6fc36..bd9639a 100644
--- a/electrum/gui/messages.py
+++ b/electrum/gui/messages.py
@@ -141,3 +141,8 @@ MSG_CONNECTMODE_ONESERVER_HELP = _(
     "This mode is only intended for connecting to your own fully trusted server. "
     "Using this option on a public server is a security risk and is discouraged."
 )
+
+MSG_RELAYFEE = ' '.join([
+    _("This transaction requires a higher fee, or it will not be propagated by your current server."),
+    _("Try to raise your transaction fee, or use a server with a lower relay fee.")
+])
diff --git a/electrum/gui/qml/components/CpfpBumpFeeDialog.qml b/electrum/gui/qml/components/CpfpBumpFeeDialog.qml
index 8361480..d68f9ed 100644
--- a/electrum/gui/qml/components/CpfpBumpFeeDialog.qml
+++ b/electrum/gui/qml/components/CpfpBumpFeeDialog.qml
@@ -153,8 +153,7 @@ ElDialog {
 
                 InfoTextArea {
                     Layout.columnSpan: 2
-                    Layout.preferredWidth: parent.width * 3/4
-                    Layout.alignment: Qt.AlignHCenter
+                    Layout.fillWidth: true
                     Layout.topMargin: constants.paddingLarge
                     visible: cpfpfeebumper.warning != ''
                     text: cpfpfeebumper.warning
diff --git a/electrum/gui/qml/components/RbfBumpFeeDialog.qml b/electrum/gui/qml/components/RbfBumpFeeDialog.qml
index f913d7a..a96add2 100644
--- a/electrum/gui/qml/components/RbfBumpFeeDialog.qml
+++ b/electrum/gui/qml/components/RbfBumpFeeDialog.qml
@@ -162,8 +162,7 @@ ElDialog {
 
                 InfoTextArea {
                     Layout.columnSpan: 2
-                    Layout.preferredWidth: parent.width * 3/4
-                    Layout.alignment: Qt.AlignHCenter
+                    Layout.fillWidth: true
                     Layout.topMargin: constants.paddingLarge
                     iconStyle: InfoTextArea.IconStyle.Warn
                     visible: rbffeebumper.warning != ''
diff --git a/electrum/gui/qml/components/RbfCancelDialog.qml b/electrum/gui/qml/components/RbfCancelDialog.qml
index a34f141..b391004 100644
--- a/electrum/gui/qml/components/RbfCancelDialog.qml
+++ b/electrum/gui/qml/components/RbfCancelDialog.qml
@@ -94,8 +94,7 @@ ElDialog {
 
                 InfoTextArea {
                     Layout.columnSpan: 2
-                    Layout.preferredWidth: parent.width * 3/4
-                    Layout.alignment: Qt.AlignHCenter
+                    Layout.fillWidth: true
                     Layout.topMargin: constants.paddingLarge
                     iconStyle: InfoTextArea.IconStyle.Warn
                     visible: txcanceller.warning != ''
diff --git a/electrum/gui/qml/components/controls/FeeMethodComboBox.qml b/electrum/gui/qml/components/controls/FeeMethodComboBox.qml
index 5c0927d..edfc850 100644
--- a/electrum/gui/qml/components/controls/FeeMethodComboBox.qml
+++ b/electrum/gui/qml/components/controls/FeeMethodComboBox.qml
@@ -14,7 +14,8 @@ ElComboBox {
     model: [
         { text: qsTr('ETA'), value: FeeSlider.FSMethod.ETA },
         { text: qsTr('Mempool'), value: FeeSlider.FSMethod.MEMPOOL },
-        { text: qsTr('Feerate'), value: FeeSlider.FSMethod.FEERATE }
+        { text: qsTr('Feerate'), value: FeeSlider.FSMethod.FEERATE },
+        { text: qsTr('Manual'), value: FeeSlider.FSMethod.MANUAL }
     ]
     onCurrentValueChanged: {
         if (activeFocus)
diff --git a/electrum/gui/qml/components/controls/FeePicker.qml b/electrum/gui/qml/components/controls/FeePicker.qml
index c8dd3b7..dedb03c 100644
--- a/electrum/gui/qml/components/controls/FeePicker.qml
+++ b/electrum/gui/qml/components/controls/FeePicker.qml
@@ -19,6 +19,8 @@ Item {
     property bool showTxInfo: true
     property bool showPicker: true
 
+    property bool manualFeeEntry: finalizer.method == FeeSlider.FSMethod.MANUAL
+
     implicitHeight: rootLayout.height
 
     GridLayout {
@@ -91,6 +93,7 @@ Item {
                 id: feeslider
                 Layout.fillWidth: true
                 leftPadding: constants.paddingMedium
+                enabled: !manualFeeEntry
 
                 snapMode: Slider.SnapOnRelease
                 stepSize: 1
@@ -117,5 +120,60 @@ Item {
                 feeslider: finalizer
             }
         }
+
+        Label {
+            Layout.preferredWidth: 1
+            text: qsTr('Rate')
+            color: Material.accentColor
+            visible: showPicker && manualFeeEntry
+        }
+
+        GridLayout {
+            Layout.preferredWidth: 2
+            Layout.rowSpan: 2
+            visible: showPicker && manualFeeEntry
+            columns: 2
+            columnSpacing: constants.paddingMedium
+
+            TextField {
+                id: rate
+                Layout.fillWidth: true
+                text: finalizer.userFeerate
+                inputMethodHints: Qt.ImhDigitsOnly
+                onTextEdited: {
+                    finalizer.userFeerate = text
+                }
+            }
+
+            Label {
+                Layout.fillWidth: true
+                color: Material.accentColor
+                text: qsTr('sat/vbyte')
+            }
+
+            TextField {
+                id: absolute
+                Layout.fillWidth: true
+                text: finalizer.userFee
+                inputMethodHints: Qt.ImhDigitsOnly
+                onTextEdited: {
+                    finalizer.userFee = text
+                }
+            }
+
+            Label {
+                Layout.fillWidth: true
+                color: Material.accentColor
+                text: qsTr('sat')
+            }
+        }
+
+        Label {
+            Layout.preferredWidth: 1
+            visible: showPicker && manualFeeEntry
+            color: Material.accentColor
+            text: qsTr('Total')
+        }
+
     }
 }
diff --git a/electrum/gui/qml/qetxfinalizer.py b/electrum/gui/qml/qetxfinalizer.py
index afd8a95..dcc6b60 100644
--- a/electrum/gui/qml/qetxfinalizer.py
+++ b/electrum/gui/qml/qetxfinalizer.py
@@ -18,6 +18,8 @@ from electrum.plugin import run_hook
 from electrum.fee_policy import FeePolicy, FeeMethod
 from electrum.network import NetworkException
 
+from electrum.gui import messages
+
 from .qewallet import QEWallet
 from .qetypes import QEAmount
 from .util import QtEventListener, event_listener
@@ -33,12 +35,14 @@ class FeeSlider(QObject):
         FEERATE = 0
         ETA = 1
         MEMPOOL = 2
+        MANUAL = 3
 
         def to_fee_method(self) -> 'FeeMethod':
             return {
                 self.FEERATE: FeeMethod.FEERATE,
                 self.ETA: FeeMethod.ETA,
                 self.MEMPOOL: FeeMethod.MEMPOOL,
+                self.MANUAL: FeeMethod.FIXED
             }[self]
 
         @classmethod
@@ -47,6 +51,7 @@ class FeeSlider(QObject):
                 FeeMethod.FEERATE: cls.FEERATE,
                 FeeMethod.ETA: cls.ETA,
                 FeeMethod.MEMPOOL: cls.MEMPOOL,
+                FeeMethod.FIXED: cls.MANUAL
             }[fm]
 
     def __init__(self, parent=None):
@@ -55,6 +60,7 @@ class FeeSlider(QObject):
         self._wallet = None  # type: Optional[QEWallet]
         self._sliderSteps = 0
         self._sliderPos = 0
+        self._fee_method = None  # type: Optional[FeeSlider.FSMethod]
         self._fee_policy = None  # type: Optional[FeePolicy]
         self._target = ''
         self._config = None  # type: Optional[SimpleConfig]
@@ -97,10 +103,9 @@ class FeeSlider(QObject):
 
     @method.setter
     def method(self, method: int):
-        fsmethod = self.FSMethod(method)
-        method = fsmethod.to_fee_method()
-        if self._fee_policy.method != method:
-            self._fee_policy.set_method(method)
+        if self._fee_method != FeeSlider.FSMethod(method):
+            self._fee_method = self.FSMethod(method)
+            self._fee_policy.set_method(self._fee_method.to_fee_method())
             self.update_slider()
             self.methodChanged.emit()
             self.save_config()
@@ -117,6 +122,8 @@ class FeeSlider(QObject):
             self.targetChanged.emit()
 
     def update_slider(self):
+        if self._fee_method == FeeSlider.FSMethod.MANUAL:
+            return
         self._sliderSteps = self._fee_policy.get_slider_max()
         self._sliderPos = self._fee_policy.get_slider_pos()
         self.sliderStepsChanged.emit()
@@ -127,16 +134,16 @@ class FeeSlider(QObject):
 
     def read_config(self):
         self._fee_policy = FeePolicy(self._config.FEE_POLICY)
+        self._fee_method = self.FSMethod.from_fee_method(self._fee_policy.method)
         self.update_slider()
         self.methodChanged.emit()
-        self.update_target()
         self.update()
 
     def save_config(self):
-        value = int(self._sliderPos)
-        self._fee_policy.set_value_from_slider_pos(value)
-        self._config.FEE_POLICY = self._fee_policy.get_descriptor()
-        self.update_target()
+        if self._fee_method != FeeSlider.FSMethod.MANUAL:
+            value = int(self._sliderPos)
+            self._fee_policy.set_value_from_slider_pos(value)
+            self._config.FEE_POLICY = self._fee_policy.get_descriptor()
         self.update()
 
     def update(self):
@@ -149,6 +156,8 @@ class TxFeeSlider(FeeSlider):
 
         self._fee = QEAmount()
         self._feeRate = ''
+        self._userFee = ''
+        self._userFeerate = ''
         self._rbf = False
         self._tx = None  # type: Optional[PartialTransaction]
         self._inputs = []
@@ -179,6 +188,37 @@ class TxFeeSlider(FeeSlider):
             self._feeRate = feeRate
             self.feeRateChanged.emit()
 
+    userFeeChanged = pyqtSignal()
+    @pyqtProperty(str, notify=userFeeChanged)
+    def userFee(self):
+        return self._userFee
+
+    @userFee.setter
+    def userFee(self, userFee):
+        if self._userFee != userFee:
+            self._logger.warn('userFee')
+            self._userFee = userFee
+            user_fee = int(userFee) if userFee else 0
+            self._fee_policy = FeePolicy(f'fixed:{user_fee}')
+            self.userFeeChanged.emit()
+            self.update()
+
+    userFeerateChanged = pyqtSignal()
+    @pyqtProperty(str, notify=userFeerateChanged)
+    def userFeerate(self):
+        return self._userFeerate
+
+    @userFeerate.setter
+    def userFeerate(self, userFeerate):
+        if self._userFeerate != userFeerate:
+            self._logger.warn('userFeerate')
+            self._userFeerate = userFeerate
+            as_decimal = Decimal(userFeerate) if userFeerate else 0
+            user_feerate = int(as_decimal * 1000)
+            self._fee_policy = FeePolicy(f'feerate:{user_feerate}')
+            self.userFeerateChanged.emit()
+            self.update()
+
     rbfChanged = pyqtSignal()
     @pyqtProperty(bool, notify=rbfChanged)
     def rbf(self):
@@ -255,6 +295,17 @@ class TxFeeSlider(FeeSlider):
 
         self.update_inputs_from_tx(tx)
         self.update_outputs_from_tx(tx)
+        self.update_target()
+        self.update_manual_fields()
+
+    def update_manual_fields(self):
+        if self._fee_method == FeeSlider.FSMethod.MANUAL:
+            if self._fee_policy.method == FeeMethod.FIXED:
+                self._userFeerate = self.feeRate
+                self.userFeerateChanged.emit()
+            else:
+                self._userFee = self.fee.satsStr
+                self.userFeeChanged.emit()
 
     def update_inputs_from_tx(self, tx: Transaction):
         inputs = []
@@ -308,6 +359,14 @@ class TxFeeSlider(FeeSlider):
         else:
             self.warning = ''
 
+    def save_config(self):
+        if self._fee_method == FeeSlider.FSMethod.MANUAL:
+            if self.fee:
+                self.userFee = self.fee.satsStr
+            if self.feeRate:
+                self.userFeerate = self.feeRate
+        super().save_config()
+
 
 class QETxFinalizer(TxFeeSlider):
     _logger = get_logger(__name__)
@@ -417,6 +476,11 @@ class QETxFinalizer(TxFeeSlider):
             self._valid = False
             self.validChanged.emit()
             return
+        except NoDynamicFeeEstimates:
+            self.warning = _('No dynamic fee estimates available')
+            self._valid = False
+            self.validChanged.emit()
+            return
         except Exception as e:
             self._logger.error(str(e))
             self.warning = repr(e)
@@ -661,12 +725,16 @@ class QETxRbfFeeBumper(TxFeeSlider, TxMonMixin):
             # not initialized yet
             return
 
-        fee_per_kb = self._fee_policy.fee_per_kb(self._wallet.wallet.network)
-        if fee_per_kb is None:
-            # dynamic method and no network
-            self._logger.debug('no fee_per_kb')
-            self.warning = _('Cannot determine dynamic fees, not connected')
-            return
+        if self._fee_policy.method == FeeMethod.FIXED:
+            fee = self._fee_policy.value
+            fee_per_kb = 1000 * fee / self._orig_tx.estimated_size()
+        else:
+            fee_per_kb = self._fee_policy.fee_per_kb(self._wallet.wallet.network)
+            if fee_per_kb is None:
+                # dynamic method and no network
+                self._logger.debug('no fee_per_kb')
+                self.warning = _('Cannot determine dynamic fees, not connected')
+                return
 
         new_fee_rate = fee_per_kb / 1000
         if new_fee_rate <= float(self._oldfee_rate):
@@ -768,12 +836,16 @@ class QETxCanceller(TxFeeSlider, TxMonMixin):
             # not initialized yet
             return
 
-        fee_per_kb = self._fee_policy.fee_per_kb(self._wallet.wallet.network)
-        if fee_per_kb is None:
-            # dynamic method and no network
-            self._logger.debug('no fee_per_kb')
-            self.warning = _('Cannot determine dynamic fees, not connected')
-            return
+        if self._fee_policy.method == FeeMethod.FIXED:
+            fee = self._fee_policy.value
+            fee_per_kb = 1000 * fee / self._orig_tx.estimated_size()
+        else:
+            fee_per_kb = self._fee_policy.fee_per_kb(self._wallet.wallet.network)
+            if fee_per_kb is None:
+                # dynamic method and no network
+                self._logger.debug('no fee_per_kb')
+                self.warning = _('Cannot determine dynamic fees, not connected')
+                return
 
         new_fee_rate = fee_per_kb / 1000
         if new_fee_rate <= float(self._oldfee_rate):
@@ -782,6 +854,13 @@ class QETxCanceller(TxFeeSlider, TxMonMixin):
             self.warning = _("The new fee rate needs to be higher than the old fee rate.")
             return
 
+        if fee_per_kb < self._wallet.wallet.relayfee():
+            self._valid = False
+            self.validChanged.emit()
+            self._logger.warning('feerate too low for relay')
+            self.warning = messages.MSG_RELAYFEE
+            return
+
         try:
             self._tx = self._wallet.wallet.dscancel(
                 tx=self._orig_tx,
@@ -895,11 +974,11 @@ class QETxCpfpFeeBumper(TxFeeSlider, TxMonMixin):
         if fee_per_kb is None:
             return None
         package_fee = FeePolicy.estimate_fee_for_feerate(fee_per_kb=fee_per_kb, size=self._total_size)
-        child_fee = package_fee - self._parent_fee
+        return self.get_child_fee_from_total_fee(package_fee)
+
+    def get_child_fee_from_total_fee(self, fee: int) -> int:
+        child_fee = fee - self._parent_fee
         child_fee = min(self._max_fee, child_fee)
-        # pay at least minrelayfee for combined size:
-        min_child_fee = FeePolicy.estimate_fee_for_feerate(fee_per_kb=self._wallet.wallet.relayfee(), size=self._total_size)
-        child_fee = max(min_child_fee, child_fee)
         return child_fee
 
     def tx_verified(self):
@@ -922,19 +1001,21 @@ class QETxCpfpFeeBumper(TxFeeSlider, TxMonMixin):
         self.validChanged.emit()
         self.warning = ''
 
-        fee_per_kb = self._fee_policy.fee_per_kb(self._wallet.wallet.network)
-        if fee_per_kb is None:
-            # dynamic method and no network
-            self._logger.debug('no fee_per_kb')
-            self.warning = _('Cannot determine dynamic fees, not connected')
-            return
-
         if self._parent_fee is None:
             self._logger.error(_("Can't CPFP: unknown fee for parent transaction."))
             self.warning = _("Can't CPFP: unknown fee for parent transaction.")
             return
 
-        fee = self.get_child_fee_from_total_feerate(fee_per_kb=fee_per_kb)
+        if self._fee_policy.method == FeeMethod.FIXED:
+            fee = self.get_child_fee_from_total_fee(self._fee_policy.value)
+        else:
+            fee_per_kb = self._fee_policy.fee_per_kb(self._wallet.wallet.network)
+            if fee_per_kb is None:
+                # dynamic method and no network
+                self._logger.debug('no fee_per_kb')
+                self.warning = _('Cannot determine dynamic fees, not connected')
+                return
+            fee = self.get_child_fee_from_total_feerate(fee_per_kb=fee_per_kb)
 
         if fee is None:
             self._logger.warning('no fee')
@@ -944,10 +1025,20 @@ class QETxCpfpFeeBumper(TxFeeSlider, TxMonMixin):
             self._logger.warning('max fee exceeded')
             self.warning = _('Max fee exceeded')
             return
+        min_child_fee = FeePolicy.estimate_fee_for_feerate(fee_per_kb=self._wallet.wallet.relayfee(), size=self._total_size)
+        if fee < min_child_fee:
+            self._logger.warning('feerate too low for relay')
+            self.warning = messages.MSG_RELAYFEE
+            return
 
         comb_fee = fee + self._parent_fee
         comb_feerate = comb_fee / self._total_size
 
+        if comb_feerate < (self._parent_fee / self._parent_tx_size):
+            self._logger.debug('combined feerate below parent tx feerate')
+            self.warning = _('Combined feerate should be greater than the parent tx feerate')
+            return
+
         self._fee.satsInt = fee
         self._output_amount.satsInt = self._max_fee - fee
         self.outputAmountChanged.emit()
@@ -967,10 +1058,21 @@ class QETxCpfpFeeBumper(TxFeeSlider, TxMonMixin):
 
         self.update_inputs_from_tx(self._new_tx)
         self.update_outputs_from_tx(self._new_tx)
+        self.update_target()
+        self.update_manual_fields()
 
         self._valid = True
         self.validChanged.emit()
 
+    def update_manual_fields(self):
+        if self._fee_method == FeeSlider.FSMethod.MANUAL:
+            if self._fee_policy.method == FeeMethod.FIXED:
+                self._userFeerate = self._total_fee_rate
+                self.userFeerateChanged.emit()
+            else:
+                self._userFee = self._total_fee.satsStr
+                self.userFeeChanged.emit()
+
     @pyqtSlot(result=str)
     def getNewTx(self):
         return str(self._new_tx)
diff --git a/electrum/util.py b/electrum/util.py
index 9cc1f33..8e5a391 100644
--- a/electrum/util.py
+++ b/electrum/util.py
@@ -891,6 +891,7 @@ UI_UNIT_NAME_FEERATE_SAT_PER_VBYTE = "sat/vbyte"
 UI_UNIT_NAME_FEERATE_SAT_PER_VB = "sat/vB"
 UI_UNIT_NAME_TXSIZE_VBYTES = "vbytes"
 UI_UNIT_NAME_MEMPOOL_MB = "vMB"
+UI_UNIT_NAME_FIXED_SAT = "sat"
 
 
 def format_fee_satoshis(fee, *, num_zeros=0, precision=None):