kivy: warn user during "Send" if high fee (change condition)

Specifically, warning was previously triggered if fee > 1 mBTC;
now it is unified with Qt, warning is triggered if feerate > 600 sat/byte.

electrum/gui/kivy/uix/screens.py

@@ -25,6 +25,7 @@ from electrum.util import send_exception_to_crash_reporter
 from electrum.paymentrequest import PR_UNPAID, PR_PAID, PR_UNKNOWN, PR_EXPIRED
 from electrum.plugin import run_hook
 from electrum.wallet import InternalAddressCorruption
+from electrum import simple_config
 
 from .context_menu import ContextMenu
 
@@ -293,7 +294,8 @@ class SendScreen(CScreen):
             x_fee_address, x_fee_amount = x_fee
             msg.append(_("Additional fees") + ": " + self.app.format_amount_and_units(x_fee_amount))
 
-        if fee >= config.get('confirm_fee', 100000):
+        feerate_warning = simple_config.FEERATE_WARNING_HIGH_FEE
+        if fee > feerate_warning * tx.estimated_size() / 1000:
             msg.append(_('Warning') + ': ' + _("The fee for this transaction seems unusually high."))
         msg.append(_("Enter your PIN code to proceed"))
         self.app.protected('\n'.join(msg), self.send_tx, (tx, message))

electrum/gui/qt/main_window.py

@@ -1683,8 +1683,8 @@ class ElectrumWindow(QMainWindow, MessageBoxMixin, Logger):
             x_fee_address, x_fee_amount = x_fee
             msg.append( _("Additional fees") + ": " + self.format_amount_and_units(x_fee_amount) )
 
-        confirm_rate = simple_config.FEERATE_WARNING_HIGH_FEE
+        feerate_warning = simple_config.FEERATE_WARNING_HIGH_FEE
-        if fee > confirm_rate * tx.estimated_size() / 1000:
+        if fee > feerate_warning * tx.estimated_size() / 1000:
             msg.append(_('Warning') + ': ' + _("The fee for this transaction seems unusually high."))
 
         if self.wallet.has_keystore_encryption():

electrum/gui/qt/transaction_dialog.py

@@ -273,8 +273,8 @@ class TxDialog(QDialog, MessageBoxMixin):
         if fee is not None:
             fee_rate = fee/size*1000
             fee_str += '  ( %s ) ' % self.main_window.format_fee_rate(fee_rate)
-            confirm_rate = simple_config.FEERATE_WARNING_HIGH_FEE
+            feerate_warning = simple_config.FEERATE_WARNING_HIGH_FEE
-            if fee_rate > confirm_rate:
+            if fee_rate > feerate_warning:
                 fee_str += ' - ' + _('Warning') + ': ' + _("high fee") + '!'
         self.amount_label.setText(amount_str)
         self.fee_label.setText(fee_str)