qt: warn user if in testnet mode

closes #5295

electrum/gui/qt/__init__.py

@@ -198,6 +198,7 @@ class ElectrumGui(PrintError):
         self.build_tray_menu()
         # FIXME: Remove in favour of the load_wallet hook
         run_hook('on_new_window', w)
+        w.warn_if_testnet()
         w.warn_if_watching_only()
         return w
 

electrum/gui/qt/main_window.py

@@ -468,7 +468,32 @@ class ElectrumWindow(QMainWindow, MessageBoxMixin, PrintError):
                 _("This means you will not be able to spend Bitcoins with it."),
                 _("Make sure you own the seed phrase or the private keys, before you request Bitcoins to be sent to this wallet.")
             ])
-            self.show_warning(msg, title=_('Information'))
+            self.show_warning(msg, title=_('Watch-only wallet'))
+
+    def warn_if_testnet(self):
+        if not constants.net.TESTNET:
+            return
+        # user might have opted out already
+        if self.config.get('dont_show_testnet_warning', False):
+            return
+        # only show once per process lifecycle
+        if getattr(self.gui_object, '_warned_testnet', False):
+            return
+        self.gui_object._warned_testnet = True
+        msg = ''.join([
+            _("You are in testnet mode."), ' ',
+            _("Testnet coins are worthless."), '\n',
+            _("Testnet is separate from the main Bitcoin network. It is used for testing.")
+        ])
+        cb = QCheckBox(_("Don't show this again."))
+        cb_checked = False
+        def on_cb(x):
+            nonlocal cb_checked
+            cb_checked = x == Qt.Checked
+        cb.stateChanged.connect(on_cb)
+        self.show_warning(msg, title=_('Testnet'), checkbox=cb)
+        if cb_checked:
+            self.config.set_key('dont_show_testnet_warning', True)
 
     def open_wallet(self):
         try:

electrum/gui/qt/util.py

@@ -218,7 +218,8 @@ class MessageBoxMixin(object):
                             title or _('Information'), msg, **kwargs)
 
     def msg_box(self, icon, parent, title, text, buttons=QMessageBox.Ok,
-                defaultButton=QMessageBox.NoButton, rich_text=False):
+                defaultButton=QMessageBox.NoButton, *, rich_text=False,
+                checkbox=None):
         parent = parent or self.top_level_window()
         if type(icon) is QPixmap:
             d = QMessageBox(QMessageBox.Information, title, str(text), buttons, parent)
@@ -233,6 +234,8 @@ class MessageBoxMixin(object):
         else:
             d.setTextInteractionFlags(Qt.TextSelectableByMouse)
             d.setTextFormat(Qt.PlainText)
+        if checkbox is not None:
+            d.setCheckBox(checkbox)
         return d.exec_()
 
 class WindowModalDialog(QDialog, MessageBoxMixin):