diff --git a/gui/qt/main_window.py b/gui/qt/main_window.py
index 0dd1980b..5cc56c3c 100644
--- a/gui/qt/main_window.py
+++ b/gui/qt/main_window.py
@@ -1165,10 +1165,12 @@ class ElectrumWindow(QMainWindow):
 
 
     @protected
-    def sign_tx(self, tx, callback, password):
+    def sign_tx(self, tx, callback, password, parent=None):
         '''Sign the transaction in a separate thread.  When done, calls
         the callback with a success code of True or False.
         '''
+        if parent == None:
+            parent = self
         self.send_button.setDisabled(True)
 
         # call hook to see if plugin needs gui interaction
@@ -1186,11 +1188,11 @@ class ElectrumWindow(QMainWindow):
             callback(success[0])
 
         # keep a reference to WaitingDialog or the gui might crash
-        self.waiting_dialog = WaitingDialog(self, 'Signing transaction...', sign_thread, on_sign_successful, on_dialog_close)
+        self.waiting_dialog = WaitingDialog(parent, 'Signing transaction...', sign_thread, on_sign_successful, on_dialog_close)
         self.waiting_dialog.start()
 
 
-    def broadcast_transaction(self, tx, tx_desc):
+    def broadcast_transaction(self, tx, tx_desc, parent=None):
 
         def broadcast_thread():
             # non-GUI thread
@@ -1217,14 +1219,16 @@ class ElectrumWindow(QMainWindow):
             if status:
                 if tx_desc is not None and tx.is_complete():
                     self.wallet.set_label(tx.hash(), tx_desc)
-                QMessageBox.information(self, '', _('Payment sent.') + '\n' + msg, _('OK'))
+                QMessageBox.information(parent, '', _('Payment sent.') + '\n' + msg, _('OK'))
                 self.update_invoices_list()
                 self.do_clear()
             else:
-                QMessageBox.warning(self, _('Error'), msg, _('OK'))
+                QMessageBox.warning(parent, _('Error'), msg, _('OK'))
             self.send_button.setDisabled(False)
 
-        self.waiting_dialog = WaitingDialog(self, 'Broadcasting transaction...', broadcast_thread, broadcast_done)
+        if parent == None:
+            parent = self
+        self.waiting_dialog = WaitingDialog(parent, 'Broadcasting transaction...', broadcast_thread, broadcast_done)
         self.waiting_dialog.start()
 
 
diff --git a/gui/qt/transaction_dialog.py b/gui/qt/transaction_dialog.py
index a58362cd..d6bd6c66 100644
--- a/gui/qt/transaction_dialog.py
+++ b/gui/qt/transaction_dialog.py
@@ -116,7 +116,7 @@ class TxDialog(QWidget):
         self.update()
 
     def do_broadcast(self):
-        self.parent.broadcast_transaction(self.tx, self.desc)
+        self.parent.broadcast_transaction(self.tx, self.desc, parent=self)
         self.broadcast = True
         self.update()
 
@@ -142,10 +142,15 @@ class TxDialog(QWidget):
 
     def sign(self):
         def sign_done(success):
+            self.sign_button.setDisabled(False)
             self.prompt_if_unsaved = True
             self.saved = False
             self.update()
-        self.parent.sign_tx(self.tx, sign_done)
+        self.sign_button.setDisabled(True)
+        cancelled, ret = self.parent.sign_tx(self.tx, sign_done, parent=self)
+        if cancelled:
+            self.sign_button.setDisabled(False)
+
 
     def save(self):
         name = 'signed_%s.txn' % (self.tx.hash()[0:8]) if self.tx.is_complete() else 'unsigned.txn'