diff --git a/gui/qt/installwizard.py b/gui/qt/installwizard.py
index 49674f8d1..104e7f445 100644
--- a/gui/qt/installwizard.py
+++ b/gui/qt/installwizard.py
@@ -407,11 +407,11 @@ class InstallWizard(WindowModalDialog, MessageBoxMixin):
         return self.exec_()
 
     def password_dialog(self):
-        msg = _("Please choose a password to encrypt your wallet keys.")+'\n'\
-              +_("Leave these fields empty if you want to disable encryption.")
-        from password_dialog import make_password_dialog, run_password_dialog
-        self.set_layout( make_password_dialog(self, None, msg) )
-        return run_password_dialog(self, None, self)[2]
+        from password_dialog import PasswordDialog
+        msg = _("Please choose a password to encrypt your wallet keys.\n"
+                "Leave these fields empty if you want to disable encryption.")
+        dialog = PasswordDialog(self, None, _("Choose a password"), msg, True)
+        return dialog.run()[2]
 
     def run(self, action):
         if self.storage.file_exists and action != 'new':
diff --git a/gui/qt/main_window.py b/gui/qt/main_window.py
index a65fa358f..c329ad93b 100644
--- a/gui/qt/main_window.py
+++ b/gui/qt/main_window.py
@@ -1852,8 +1852,39 @@ class ElectrumWindow(QMainWindow, MessageBoxMixin, PrintError):
 
     def change_password_dialog(self):
         from password_dialog import PasswordDialog
-        d = PasswordDialog(self.wallet, self)
-        d.run()
+
+        if self.wallet and self.wallet.is_watching_only():
+            self.show_error(_('This is a watching-only wallet'))
+            return
+
+        msg = (_('Your wallet is encrypted. Use this dialog to change your '
+                 'password. To disable wallet encryption, enter an empty new '
+                 'password.') if self.wallet.use_encryption
+               else _('Your wallet keys are not encrypted'))
+        d = PasswordDialog(self, self.wallet, _("Set Password"), msg, True)
+        ok, password, new_password = d.run()
+        if not ok:
+            return
+
+        try:
+            self.wallet.check_password(password)
+        except BaseException as e:
+            self.show_error(str(e))
+            return
+
+        try:
+            self.wallet.update_password(password, new_password)
+        except:
+            traceback.print_exc(file=sys.stdout)
+            self.show_error(_('Failed to update password'))
+            return
+
+        if new_password:
+            msg = _('Password was updated successfully')
+        else:
+            msg = _('This wallet is not encrypted')
+        self.show_message(msg, title=_("Success"))
+
         self.update_lock_icon()
 
     def toggle_search(self):
diff --git a/gui/qt/password_dialog.py b/gui/qt/password_dialog.py
index 104cc94d1..6f0b975bc 100644
--- a/gui/qt/password_dialog.py
+++ b/gui/qt/password_dialog.py
@@ -23,84 +23,6 @@ from util import *
 import re
 import math
 
-
-
-def make_password_dialog(self, wallet, msg, new_pass=True):
-
-    self.pw = QLineEdit()
-    self.pw.setEchoMode(2)
-    self.new_pw = QLineEdit()
-    self.new_pw.setEchoMode(2)
-    self.conf_pw = QLineEdit()
-    self.conf_pw.setEchoMode(2)
-
-    vbox = QVBoxLayout()
-    label = QLabel(msg)
-    label.setWordWrap(True)
-
-    grid = QGridLayout()
-    grid.setSpacing(8)
-    grid.setColumnMinimumWidth(0, 70)
-    grid.setColumnStretch(1,1)
-
-    logo = QLabel()
-    lockfile = ":icons/lock.png" if wallet and wallet.use_encryption else ":icons/unlock.png"
-    logo.setPixmap(QPixmap(lockfile).scaledToWidth(36))
-    logo.setAlignment(Qt.AlignCenter)
-
-    grid.addWidget(logo,  0, 0)
-    grid.addWidget(label, 0, 1, 1, 2)
-    vbox.addLayout(grid)
-
-    grid = QGridLayout()
-    grid.setSpacing(8)
-    grid.setColumnMinimumWidth(0, 250)
-    grid.setColumnStretch(1,1)
-
-    if wallet and wallet.use_encryption:
-        grid.addWidget(QLabel(_('Password')), 0, 0)
-        grid.addWidget(self.pw, 0, 1)
-
-    grid.addWidget(QLabel(_('New Password') if new_pass else _('Password')), 1, 0)
-    grid.addWidget(self.new_pw, 1, 1)
-
-    grid.addWidget(QLabel(_('Confirm Password')), 2, 0)
-    grid.addWidget(self.conf_pw, 2, 1)
-    vbox.addLayout(grid)
-
-    #Password Strength Label
-    self.pw_strength = QLabel()
-    grid.addWidget(self.pw_strength, 3, 0, 1, 2)
-    self.new_pw.textChanged.connect(lambda: update_password_strength(self.pw_strength, self.new_pw.text()))
-
-    vbox.addStretch(1)
-    vbox.addLayout(Buttons(CancelButton(self), OkButton(self)))
-    return vbox
-
-
-def run_password_dialog(self, wallet, parent):
-
-    if wallet and wallet.is_watching_only():
-        QMessageBox.information(parent, _('Error'), _('This is a watching-only wallet'), _('OK'))
-        return False, None, None
-
-    if not self.exec_():
-        return False, None, None
-
-    password = unicode(self.pw.text()) if wallet and wallet.use_encryption else None
-    new_password = unicode(self.new_pw.text())
-    new_password2 = unicode(self.conf_pw.text())
-
-    if new_password != new_password2:
-        QMessageBox.warning(parent, _('Error'), _('Passwords do not match'), _('OK'))
-        # Retry
-        return run_password_dialog(self, wallet, parent)
-
-    if not new_password:
-        new_password = None
-
-    return True, password, new_password
-
 def check_password_strength(password):
 
     '''
@@ -117,57 +39,89 @@ def check_password_strength(password):
     password_strength = {0:"Weak",1:"Medium",2:"Strong",3:"Very Strong"}
     return password_strength[min(3, int(score))]
 
-
-def update_password_strength(pw_strength_label,password):
-
-    '''
-    call the function check_password_strength and update the label pw_strength interactively as the user is typing the password
-    :param pw_strength_label: the label pw_strength
-    :param password: password entered in New Password text box
-    :return: None
-    '''
-    if password:
-        colors = {"Weak":"Red","Medium":"Blue","Strong":"Green", "Very Strong":"Green"}
-        strength = check_password_strength(password)
-        label = _("Password Strength")+ ": "+"<font color=" + colors[strength] + ">" + strength + "</font>"
-    else:
-        label = ""
-    pw_strength_label.setText(label)
-
-
-
 class PasswordDialog(WindowModalDialog):
 
-    def __init__(self, wallet, parent):
-        WindowModalDialog.__init__(self, parent,_("Set Password"))
+    def __init__(self, parent, wallet, title, msg, new_pass):
+        WindowModalDialog.__init__(self, parent, title)
         self.wallet = wallet
-        self.parent = parent
-        msg = (_('Your wallet is encrypted. Use this dialog to change your password.') + ' '\
-               +_('To disable wallet encryption, enter an empty new password.')) \
-               if wallet.use_encryption else _('Your wallet keys are not encrypted')
-        self.setLayout(make_password_dialog(self, wallet, msg))
 
+        self.pw = QLineEdit()
+        self.pw.setEchoMode(2)
+        self.new_pw = QLineEdit()
+        self.new_pw.setEchoMode(2)
+        self.conf_pw = QLineEdit()
+        self.conf_pw.setEchoMode(2)
+
+        vbox = QVBoxLayout()
+        label = QLabel(msg)
+        label.setWordWrap(True)
+
+        grid = QGridLayout()
+        grid.setSpacing(8)
+        grid.setColumnMinimumWidth(0, 70)
+        grid.setColumnStretch(1,1)
+
+        logo = QLabel()
+        logo.setAlignment(Qt.AlignCenter)
+
+        grid.addWidget(logo,  0, 0)
+        grid.addWidget(label, 0, 1, 1, 2)
+        vbox.addLayout(grid)
+
+        grid = QGridLayout()
+        grid.setSpacing(8)
+        grid.setColumnMinimumWidth(0, 250)
+        grid.setColumnStretch(1,1)
+
+        if wallet and wallet.use_encryption:
+            grid.addWidget(QLabel(_('Password')), 0, 0)
+            grid.addWidget(self.pw, 0, 1)
+            lockfile = ":icons/lock.png"
+        else:
+            self.pw = None
+            lockfile = ":icons/unlock.png"
+        logo.setPixmap(QPixmap(lockfile).scaledToWidth(36))
+
+        grid.addWidget(QLabel(_('New Password') if new_pass else _('Password')), 1, 0)
+        grid.addWidget(self.new_pw, 1, 1)
+
+        grid.addWidget(QLabel(_('Confirm Password')), 2, 0)
+        grid.addWidget(self.conf_pw, 2, 1)
+        vbox.addLayout(grid)
+
+        # Password Strength Label
+        self.pw_strength = QLabel()
+        grid.addWidget(self.pw_strength, 3, 0, 1, 2)
+        self.new_pw.textChanged.connect(self.pw_changed)
+        self.conf_pw.textChanged.connect(self.check_OKButton)
+
+        self.OKButton = OkButton(self)
+        vbox.addStretch(1)
+        vbox.addLayout(Buttons(CancelButton(self), self.OKButton))
+        self.setLayout(vbox)
+
+    def pw_changed(self):
+        password = self.new_pw.text()
+        if password:
+            colors = {"Weak":"Red", "Medium":"Blue", "Strong":"Green",
+                      "Very Strong":"Green"}
+            strength = check_password_strength(password)
+            label = (_("Password Strength") + ": " + "<font color="
+                     + colors[strength] + ">" + strength + "</font>")
+        else:
+            label = ""
+        self.pw_strength.setText(label)
+        self.check_OKButton()
+
+    def check_OKButton(self):
+        self.OKButton.setEnabled(self.new_pw.text() == self.conf_pw.text())
 
     def run(self):
-        ok, password, new_password = run_password_dialog(self, self.wallet, self.parent)
-        if not ok:
-            return
-
-        try:
-            self.wallet.check_password(password)
-        except BaseException as e:
-            QMessageBox.warning(self.parent, _('Error'), str(e), _('OK'))
+        if not self.exec_():
             return False, None, None
 
-        try:
-            self.wallet.update_password(password, new_password)
-        except:
-            import traceback, sys
-            traceback.print_exc(file=sys.stdout)
-            QMessageBox.warning(self.parent, _('Error'), _('Failed to update password'), _('OK'))
-            return
+        password = unicode(self.pw.text()) if self.pw else None
+        new_password = unicode(self.new_pw.text())
+        new_password2 = unicode(self.conf_pw.text())
 
-        if new_password:
-            QMessageBox.information(self.parent, _('Success'), _('Password was updated successfully'), _('OK'))
-        else:
-            QMessageBox.information(self.parent, _('Success'), _('This wallet is not encrypted'), _('OK'))
+        return True, password or None, new_password or None
diff --git a/plugins/keepkey/qt.py b/plugins/keepkey/qt.py
index ab6ce807a..db842b577 100644
--- a/plugins/keepkey/qt.py
+++ b/plugins/keepkey/qt.py
@@ -1,4 +1,4 @@
-from PyQt4.Qt import QMessageBox, QDialog, QVBoxLayout, QLabel, QThread, SIGNAL, QGridLayout, QInputDialog, QPushButton
+from PyQt4.Qt import QMessageBox, QVBoxLayout, QLabel, QThread, SIGNAL, QGridLayout, QInputDialog, QPushButton
 import PyQt4.QtCore as QtCore
 from electrum_gui.qt.util import *
 from electrum_gui.qt.main_window import StatusBarButton, ElectrumWindow
@@ -73,7 +73,7 @@ class Plugin(KeepKeyPlugin):
             return
         get_label = lambda: self.get_client().features.label
         update_label = lambda: current_label_label.setText("Label: %s" % get_label())
-        d = QDialog()
+        d = WindowModalDialog(window, _("KeepKey Settings"))
         layout = QGridLayout(d)
         layout.addWidget(QLabel("KeepKey Options"),0,0)
         layout.addWidget(QLabel("ID:"),1,0)
@@ -132,10 +132,7 @@ class KeepKeyQtHandler:
         return self.passphrase
 
     def pin_dialog(self):
-        d = QDialog(None)
-        d.setModal(1)
-        d.setWindowTitle(_("Enter PIN"))
-        d.setWindowFlags(d.windowFlags() | QtCore.Qt.WindowStaysOnTopHint)
+        d = WindowModalDialog(self.win, _("Enter PIN"))
         matrix = PinMatrixWidget()
         vbox = QVBoxLayout()
         vbox.addWidget(QLabel(self.message))
@@ -153,23 +150,18 @@ class KeepKeyQtHandler:
             self.passphrase = unicodedata.normalize('NFKD', unicode(passphrase)) if passphrase else ''
         else:
             assert type(self.win) is InstallWizard
-            from electrum_gui.qt.password_dialog import make_password_dialog, run_password_dialog
-            d = QDialog()
-            d.setModal(1)
-            d.setLayout(make_password_dialog(d, None, self.message, False))
-            confirmed, p, passphrase = run_password_dialog(d, None, None)
+            from electrum_gui.qt.password_dialog import PasswordDialog
+            d = PasswordDialog(self.win, None, None, self.message, False)
+            confirmed, p, passphrase = d.run()
             if not confirmed:
-                QMessageBox.critical(None, _('Error'), _("Password request canceled"), _('OK'))
+                self.win.show_critical(_("Password request canceled"))
                 self.passphrase = None
             else:
                 self.passphrase = unicodedata.normalize('NFKD', unicode(passphrase)) if passphrase else ''
         self.done.set()
 
     def message_dialog(self):
-        self.d = QDialog()
-        self.d.setModal(1)
-        self.d.setWindowTitle('Please Check KeepKey Device')
-        self.d.setWindowFlags(self.d.windowFlags() | QtCore.Qt.WindowStaysOnTopHint)
+        self.d = WindowModalDialog(self.win, _('Please Check KeepKey Device'))
         l = QLabel(self.message)
         vbox = QVBoxLayout(self.d)
         vbox.addWidget(l)
@@ -182,5 +174,3 @@ class KeepKeyQtHandler:
 
     def dialog_stop(self):
         self.d.hide()
-
-
diff --git a/plugins/trezor/qt.py b/plugins/trezor/qt.py
index 0926b331b..eb11f0620 100644
--- a/plugins/trezor/qt.py
+++ b/plugins/trezor/qt.py
@@ -1,4 +1,4 @@
-from PyQt4.Qt import QMessageBox, QDialog, QVBoxLayout, QLabel, QThread, SIGNAL, QGridLayout, QInputDialog, QPushButton
+from PyQt4.Qt import QMessageBox, QVBoxLayout, QLabel, QThread, SIGNAL, QGridLayout, QInputDialog, QPushButton
 import PyQt4.QtCore as QtCore
 from electrum_gui.qt.util import *
 from electrum_gui.qt.main_window import StatusBarButton, ElectrumWindow
@@ -46,10 +46,7 @@ class TrezorQtHandler:
         return self.passphrase
 
     def pin_dialog(self):
-        d = QDialog(None)
-        d.setModal(1)
-        d.setWindowTitle(_("Enter PIN"))
-        d.setWindowFlags(d.windowFlags() | QtCore.Qt.WindowStaysOnTopHint)
+        d = WindowModalDialog(self.win, _("Enter PIN"))
         matrix = PinMatrixWidget()
         vbox = QVBoxLayout()
         vbox.addWidget(QLabel(self.message))
@@ -67,23 +64,18 @@ class TrezorQtHandler:
             self.passphrase = unicodedata.normalize('NFKD', unicode(passphrase)) if passphrase else ''
         else:
             assert type(self.win) is InstallWizard
-            from electrum_gui.qt.password_dialog import make_password_dialog, run_password_dialog
-            d = QDialog()
-            d.setModal(1)
-            d.setLayout(make_password_dialog(d, None, self.message, False))
-            confirmed, p, passphrase = run_password_dialog(d, None, None)
+            from electrum_gui.qt.password_dialog import PasswordDialog
+            d = PasswordDialog(self.win, None, None, self.message, False)
+            confirmed, p, passphrase = d.run()
             if not confirmed:
-                QMessageBox.critical(None, _('Error'), _("Password request canceled"), _('OK'))
+                self.win.show_critical(_("Password request canceled"))
                 self.passphrase = None
             else:
                 self.passphrase = unicodedata.normalize('NFKD', unicode(passphrase)) if passphrase else ''
         self.done.set()
 
     def message_dialog(self):
-        self.d = QDialog()
-        self.d.setModal(1)
-        self.d.setWindowTitle('Please Check Trezor Device')
-        self.d.setWindowFlags(self.d.windowFlags() | QtCore.Qt.WindowStaysOnTopHint)
+        self.d = WindowModalDialog(self.win, _('Please Check Trezor Device'))
         l = QLabel(self.message)
         vbox = QVBoxLayout(self.d)
         vbox.addWidget(l)
@@ -171,7 +163,7 @@ class Plugin(TrezorPlugin):
             return
         get_label = lambda: self.get_client().features.label
         update_label = lambda: current_label_label.setText("Label: %s" % get_label())
-        d = QDialog()
+        d = WindowModalDialog(window, _("Trezor Settings"))
         layout = QGridLayout(d)
         layout.addWidget(QLabel("Trezor Options"),0,0)
         layout.addWidget(QLabel("ID:"),1,0)