Have show-before-broadcast defer password request

Show-before-send currently asks for the password
and creates a signed tx before showing anything.

This is a little unnerving as you can't see what
you're being asked to sign.

This patch does a few things:

- Adds a description label to the TX dialog
- You see the tx before being asked for password;
  that is only requested on pressing Sign
- in show-before-broadcast mode, the Send button
  text is instead "Show...".  Hook up this button
  text change to the prefs dialog too.
- Remove many redundant imports.  In particular
  PyQ4 is checked in main_window.py so no need
  in tx_dialog too.

Note I had to remove disabling of the Sign button,
because if the user presses "cancel" nothing will
re-enable it.

gui/qt/main_window.py

@@ -16,13 +16,9 @@
 # You should have received a copy of the GNU General Public License
 # along with this program. If not, see <http://www.gnu.org/licenses/>.
 
-import sys, time, re, threading
+import sys, time, threading
-from electrum.i18n import _, set_language
+import os.path, json, traceback
-from electrum.util import block_explorer, block_explorer_info, block_explorer_URL
-from electrum.util import print_error, print_msg
-import os.path, json, ast, traceback
 import shutil
-import StringIO
 
 
 import PyQt4
@@ -35,6 +31,9 @@ from electrum.plugins import run_hook
 
 import icons_rc
 
+from electrum.i18n import _
+from electrum.util import block_explorer, block_explorer_info, block_explorer_URL
+from electrum.util import print_error, print_msg
 from electrum.util import format_satoshis, format_satoshis_plain, format_time, NotEnoughFunds, StoreDict
 from electrum import Transaction
 from electrum import mnemonic
@@ -299,7 +298,6 @@ class ElectrumWindow(QMainWindow):
 
 
     def backup_wallet(self):
-        import shutil
         path = self.wallet.storage.path
         wallet_folder = os.path.dirname(path)
         filename = unicode( QFileDialog.getSaveFileName(self, _('Enter a filename for the copy of your wallet'), wallet_folder) )
@@ -570,9 +568,10 @@ class ElectrumWindow(QMainWindow):
         d = address_dialog.AddressDialog(addr, self)
         d.exec_()
 
-    def show_transaction(self, tx):
+    def show_transaction(self, tx, tx_desc = None):
+        '''tx_desc is set only for txs created in the Send tab'''
         import transaction_dialog
-        d = transaction_dialog.TxDialog(tx, self)
+        d = transaction_dialog.TxDialog(tx, self, tx_desc)
         d.show()
 
     def update_history_tab(self):
@@ -835,6 +834,21 @@ class ElectrumWindow(QMainWindow):
         if self.qr_window and self.qr_window.isVisible():
             self.qr_window.set_content(addr, amount, message, uri)
 
+    def show_before_broadcast(self):
+        return self.config.get('show_before_broadcast', False)
+
+    def set_show_before_broadcast(self, show):
+        self.config.set_key('show_before_broadcast', bool(show))
+        self.set_send_button_text()
+
+    def set_send_button_text(self):
+        if self.show_before_broadcast():
+            text = _("Show...")
+        elif self.wallet.is_watching_only():
+            text = _("Create unsigned transaction")
+        else:
+            text = _("Send")
+        self.send_button.setText(text)
 
     def create_send_tab(self):
         self.send_grid = grid = QGridLayout()
@@ -888,7 +902,8 @@ class ElectrumWindow(QMainWindow):
         grid.addWidget(self.fee_e_label, 5, 0)
         grid.addWidget(self.fee_e, 5, 1, 1, 2)
 
-        self.send_button = EnterButton(_("Send"), self.do_send)
+        self.send_button = EnterButton('', self.do_send)
+        self.set_send_button_text()
         self.clear_button = EnterButton(_("Clear"), self.do_clear)
         buttons = QHBoxLayout()
         buttons.addStretch(1)
@@ -1096,14 +1111,16 @@ class ElectrumWindow(QMainWindow):
                 if not self.question(_("The fee for this transaction seems unusually high.\nAre you really sure you want to pay %(fee)s in fees?")%{ 'fee' : self.format_amount(fee) + ' '+ self.base_unit()}):
                     return
 
+        if self.show_before_broadcast():
+            self.show_transaction(tx, tx_desc)
+        else:
             def sign_done(success):
                 if success:
-                if not tx.is_complete() or self.config.get('show_before_broadcast'):
+                    if not tx.is_complete():
                         self.show_transaction(tx)
                         self.do_clear()
                     else:
                         self.broadcast_transaction(tx, tx_desc)
-
             self.send_tx(tx, sign_done)
 
 
@@ -1133,7 +1150,6 @@ class ElectrumWindow(QMainWindow):
         self.waiting_dialog.start()
 
 
-
     def broadcast_transaction(self, tx, tx_desc):
 
         def broadcast_thread():
@@ -1670,7 +1686,7 @@ class ElectrumWindow(QMainWindow):
     def update_buttons_on_seed(self):
         self.seed_button.setVisible(self.wallet.has_seed())
         self.password_button.setVisible(self.wallet.can_change_password())
-        self.send_button.setText(_("Create unsigned transaction") if self.wallet.is_watching_only() else _("Send"))
+        self.set_send_button_text()
 
 
     def change_password_dialog(self):
@@ -2539,8 +2555,8 @@ class ElectrumWindow(QMainWindow):
         widgets.append((usechange_cb, None, usechange_help))
 
         showtx_cb = QCheckBox(_('Show transaction before broadcast'))
-        showtx_cb.setChecked(self.config.get('show_before_broadcast', False))
+        showtx_cb.setChecked(self.show_before_broadcast())
-        showtx_cb.stateChanged.connect(lambda x: self.config.set_key('show_before_broadcast', showtx_cb.isChecked()))
+        showtx_cb.stateChanged.connect(lambda x: self.set_show_before_broadcast(showtx_cb.isChecked()))
         showtx_help = HelpButton(_('Display the details of your transactions before broadcasting it.'))
         widgets.append((showtx_cb, None, showtx_help))
 

gui/qt/transaction_dialog.py

@@ -16,25 +16,17 @@
 # You should have received a copy of the GNU General Public License
 # along with this program. If not, see <http://www.gnu.org/licenses/>.
 
-import sys, time, datetime, re, threading
+import datetime
-from electrum.i18n import _, set_language
+import json
-from electrum.util import print_error, print_msg
-import os.path, json, ast, traceback
-import shutil
-import StringIO
 
-
-try:
 import PyQt4
-except Exception:
-    sys.exit("Error: Could not import PyQt4 on Linux systems, you may try 'sudo apt-get install python-qt4'")
-
 from PyQt4.QtGui import *
 from PyQt4.QtCore import *
 import PyQt4.QtCore as QtCore
 
 from electrum import transaction
 from electrum.bitcoin import base_encode
+from electrum.i18n import _
 from electrum.plugins import run_hook
 
 from util import *
@@ -42,12 +34,16 @@ from util import *
 
 class TxDialog(QWidget):
 
-    def __init__(self, tx, parent):
+    def __init__(self, tx, parent, desc=None):
+        '''Transactions in the wallet will show their description.
+        Pass desc to give a description for txs not yet in the wallet.
+        '''
         self.tx = tx
         tx_dict = tx.as_dict()
         self.parent = parent
         self.wallet = parent.wallet
         self.saved = True
+        self.desc = desc
 
         QWidget.__init__(self)
         self.setMinimumWidth(600)
@@ -65,6 +61,8 @@ class TxDialog(QWidget):
         self.status_label = QLabel()
         vbox.addWidget(self.status_label)
 
+        self.tx_desc = QLabel()
+        vbox.addWidget(self.tx_desc)
         self.date_label = QLabel()
         vbox.addWidget(self.date_label)
         self.amount_label = QLabel()
@@ -125,9 +123,7 @@ class TxDialog(QWidget):
 
     def sign(self):
         def sign_done(success):
-            self.sign_button.setDisabled(False)
             self.update()
-        self.sign_button.setDisabled(True)
         self.parent.send_tx(self.tx, sign_done)
 
     def save(self):
@@ -143,6 +139,7 @@ class TxDialog(QWidget):
     def update(self):
         is_relevant, is_mine, v, fee = self.wallet.get_wallet_delta(self.tx)
         tx_hash = self.tx.hash()
+        desc = self.desc
         if self.wallet.can_sign(self.tx):
             self.sign_button.show()
         else:
@@ -152,6 +149,7 @@ class TxDialog(QWidget):
             status = _("Signed")
 
             if tx_hash in self.wallet.transactions.keys():
+                desc, is_default = self.wallet.get_label(tx_hash)
                 conf, timestamp = self.wallet.get_confirmations(tx_hash)
                 if timestamp:
                     time_str = datetime.datetime.fromtimestamp(timestamp).isoformat(' ')[:-3]
@@ -171,6 +169,11 @@ class TxDialog(QWidget):
             tx_hash = 'unknown'
 
         self.tx_hash_e.setText(tx_hash)
+        if desc is None:
+            self.tx_desc.hide()
+        else:
+            self.tx_desc.setText(_("Description") + ': ' + desc)
+            self.tx_desc.show()
         self.status_label.setText(_('Status:') + ' ' + status)
 
         if time_str is not None: