SwapProvidersButton class

diff --git a/electrum/gui/qt/confirm_tx_dialog.py b/electrum/gui/qt/confirm_tx_dialog.py
index 3935db7..3961c09 100644
--- a/electrum/gui/qt/confirm_tx_dialog.py
+++ b/electrum/gui/qt/confirm_tx_dialog.py
@@ -28,7 +28,6 @@ from decimal import Decimal
 from functools import partial
 from typing import TYPE_CHECKING, Optional, Union
 
-from electrum_aionostr.util import from_nip19
 from PyQt6.QtCore import Qt, QTimer
 from PyQt6.QtGui import QIcon
 from PyQt6.QtWidgets import (QHBoxLayout, QVBoxLayout, QLabel, QGridLayout, QPushButton, QToolButton,
@@ -47,14 +46,13 @@ from electrum.submarine_swaps import NostrTransport, HttpTransport
 from .seed_dialog import seed_warning_msg
 
 from .util import (WindowModalDialog, ColorScheme, HelpLabel, Buttons, CancelButton, WWLabel,
-                   read_QIcon, debug_widget_layouts, qt_event_listener, QtEventListener, IconLabel,
-                   pubkey_to_q_icon)
+                   read_QIcon, debug_widget_layouts, qt_event_listener, QtEventListener, IconLabel)
 from .transaction_dialog import TxSizeLabel, TxFiatLabel, TxInOutWidget
 from .fee_slider import FeeSlider, FeeComboBox
 from .amountedit import FeerateEdit, BTCAmountEdit
 from .locktimeedit import LockTimeEdit
 from .my_treeview import QMenuWithConfig
-from .swap_dialog import SwapServerDialog
+from .swap_dialog import SwapProvidersButton
 
 if TYPE_CHECKING:
     from .main_window import ElectrumWindow
@@ -303,7 +301,7 @@ class TxEditor(WindowModalDialog, QtEventListener, Logger):
             self.tab_widget.removeTab(0)
 
         # always show onchain payment tab
-        self.tab_widget.addTab(self.onchain_tab, _('Onchain'))
+        self.tab_widget.addTab(self.onchain_tab, _('Onchain Transaction'))
 
         allow_swaps = self.allow_preview and self.payee_outputs  # allow_preview is false for ln channel opening txs
         if self.config.WALLET_ENABLE_SUBMARINE_PAYMENTS and allow_swaps:
@@ -728,10 +726,7 @@ class TxEditor(WindowModalDialog, QtEventListener, Logger):
         vbox.addWidget(self.submarine_stacked_widget)
         vbox.addStretch(1)
 
-        self.server_button = QPushButton()
-        self.server_button.clicked.connect(self.choose_swap_server)
-        self.server_button.setEnabled(False)
-        self.server_button.setVisible(False)
+        self.server_button = SwapProvidersButton(lambda: self.swap_transport, self.config, self.main_window)
 
         self.submarine_ok_button = QPushButton(_('OK'))
         self.submarine_ok_button.setDefault(True)
@@ -830,9 +825,8 @@ class TxEditor(WindowModalDialog, QtEventListener, Logger):
         # we couldn't even connect to the relays, this transport is useless. maybe network issues.
         return False
 
-    def choose_swap_server(self) -> None:
-        assert isinstance(self.swap_transport, NostrTransport), self.swap_transport
-        self.main_window.choose_swapserver_dialog(self.swap_transport)
+    @qt_event_listener
+    def on_event_swap_provider_changed(self):
         self.update_submarine_tab()
 
     def start_submarine_swap(self):
@@ -881,20 +875,7 @@ class TxEditor(WindowModalDialog, QtEventListener, Logger):
             return
 
         # Update the swapserver selection button text
-        if isinstance(self.swap_transport, NostrTransport):
-            self.server_button.setVisible(True)
-            self.server_button.setEnabled(True)
-            if self.config.SWAPSERVER_NPUB:
-                pubkey = from_nip19(self.config.SWAPSERVER_NPUB)['object'].hex()
-                self.server_button.setIcon(pubkey_to_q_icon(pubkey))
-            self.server_button.setText(
-                f' {len(self.swap_transport.get_recent_offers())} ' +
-                (_('providers') if len(self.swap_transport.get_recent_offers()) != 1 else _('provider'))
-            )
-        else:
-            # HTTPTransport or no Network, not showing server selection button
-            self.server_button.setEnabled(False)
-            self.server_button.setVisible(False)
+        self.server_button.update()
 
         if not self.swap_manager.is_initialized.is_set():
             # connected to nostr relays but couldn't find swapserver announcement
@@ -996,6 +977,7 @@ class TxEditor(WindowModalDialog, QtEventListener, Logger):
 
     @qt_event_listener
     def on_event_swap_offers_changed(self, _):
+        self.server_button.update()
         if self.ongoing_swap_transport_connection_attempt \
                 and not self.ongoing_swap_transport_connection_attempt.done():
             return
diff --git a/electrum/gui/qt/swap_dialog.py b/electrum/gui/qt/swap_dialog.py
index cfa85b9..4c501f4 100644
--- a/electrum/gui/qt/swap_dialog.py
+++ b/electrum/gui/qt/swap_dialog.py
@@ -9,7 +9,7 @@ from PyQt6.QtWidgets import QTreeWidget, QTreeWidgetItem, QHeaderView
 from electrum_aionostr.util import from_nip19
 
 from electrum.i18n import _
-from electrum.util import NotEnoughFunds, NoDynamicFeeEstimates, UserCancelled
+from electrum.util import NotEnoughFunds, NoDynamicFeeEstimates, UserCancelled, trigger_callback
 from electrum.bitcoin import DummyAddress
 from electrum.transaction import PartialTxOutput, PartialTransaction
 from electrum.fee_policy import FeePolicy
@@ -43,6 +43,43 @@ ROLE_NPUB = Qt.ItemDataRole.UserRole + 1000
 class InvalidSwapParameters(Exception): pass
 
 
+class SwapProvidersButton(QPushButton):
+
+    def __init__(self, transport_getter, config, main_window):
+        """parent must have a transport() method"""
+        QPushButton.__init__(self)
+        self.config = config
+        self.transport_getter = transport_getter
+        self.main_window = main_window
+        self.clicked.connect(self.choose_swap_server)
+        self.update()
+
+    def update(self):
+        transport = self.transport_getter()
+        if not isinstance(transport, NostrTransport):
+            # HTTPTransport or no Network, not showing server selection button
+            self.setEnabled(False)
+            self.setVisible(False)
+            return
+        self.setEnabled(True)
+        self.setVisible(True)
+        offer_count = len(transport.get_recent_offers())
+        button_text = f' {offer_count} ' + (_('swap providers') if offer_count != 1 else _('swap provider'))
+        self.setText(button_text)
+        # update icon
+        if self.config.SWAPSERVER_NPUB:
+            pubkey = from_nip19(self.config.SWAPSERVER_NPUB)['object'].hex()
+            self.setIcon(pubkey_to_q_icon(pubkey))
+
+    def choose_swap_server(self) -> None:
+        transport = self.transport_getter()
+        assert isinstance(transport, NostrTransport), transport
+        self.main_window.choose_swapserver_dialog(transport)  # type: ignore
+        self.update()
+        trigger_callback('swap_provider_changed')
+
+
+
 class SwapDialog(WindowModalDialog, QtEventListener):
 
     def __init__(
@@ -63,12 +100,8 @@ class SwapDialog(WindowModalDialog, QtEventListener):
         self.is_reverse = is_reverse if is_reverse is not None else True
         vbox = QVBoxLayout(self)
 
-        self.server_button = QPushButton()
-        self.set_server_button_text(len(transport.get_recent_offers()) \
-            if not self.config.SWAPSERVER_URL and isinstance(transport, NostrTransport) else 0
-        )
-        self.server_button.clicked.connect(lambda: self.choose_swap_server(transport))
-        self.server_button.setEnabled(not self.config.SWAPSERVER_URL)
+        self.transport = transport
+        self.server_button = SwapProvidersButton(lambda: self.transport, self.config, self.window)
         self.description_label = WWLabel(self.get_description())
         self.send_amount_e = BTCAmountEdit(self.window.get_decimal_point)
         self.recv_amount_e = BTCAmountEdit(self.window.get_decimal_point)
@@ -158,7 +191,7 @@ class SwapDialog(WindowModalDialog, QtEventListener):
 
     @qt_event_listener
     def on_event_swap_offers_changed(self, recent_offers: Sequence['SwapOffer']):
-        self.set_server_button_text(len(recent_offers))
+        self.server_button.update()
         if not self.ok_button.isEnabled():
             # only update the dialog with the new offer if the user hasn't entered an amount yet.
             # if the user has already entered an amount we prefer the swap to fail due to outdated
@@ -166,9 +199,10 @@ class SwapDialog(WindowModalDialog, QtEventListener):
             # due to an update happening just before the user initiated the swap
             self.update()
 
-    def set_server_button_text(self, offer_count: int):
-        button_text = f' {offer_count} ' + (_('providers') if offer_count != 1 else _('provider'))
-        self.server_button.setText(button_text)
+    @qt_event_listener
+    def on_event_swap_provider_changed(self):
+        self.update()
+        self.update_send_receive()
 
     def timer_actions(self):
         if self.needs_tx_update:
@@ -298,9 +332,6 @@ class SwapDialog(WindowModalDialog, QtEventListener):
         self.server_fee_label.setText(server_fee_str)
         self.server_fee_label.repaint()  # macOS hack for #6269
         self.needs_tx_update = True
-        # update icon
-        pubkey = from_nip19(self.config.SWAPSERVER_NPUB)['object'].hex() if self.config.SWAPSERVER_NPUB else ''
-        self.server_button.setIcon(pubkey_to_q_icon(pubkey))
 
     def get_client_swap_limits_sat(self) -> Tuple[int, int]:
         """Returns the (min, max) client swap limits in sat."""
@@ -452,11 +483,6 @@ class SwapDialog(WindowModalDialog, QtEventListener):
             capacityType="receiving" if self.is_reverse else "sending",
         )
 
-    def choose_swap_server(self, transport: 'SwapServerTransport') -> None:
-        self.window.choose_swapserver_dialog(transport)  # type: ignore
-        self.update()
-        self.update_send_receive()
-
 
 class SwapServerDialog(WindowModalDialog, QtEventListener):