addons: add option to restart Orange after new add-on is installed

Orange/canvas/application/addons.py

@@ -28,7 +28,7 @@
     QWidget, QDialog, QLabel, QLineEdit, QTreeView, QHeaderView,
     QTextBrowser, QDialogButtonBox, QProgressDialog,
     QVBoxLayout, QStyle, QStyledItemDelegate, QStyleOptionViewItem,
-    QApplication, QHBoxLayout, QPushButton, QFormLayout
+    QApplication, QHBoxLayout, QPushButton, QFormLayout, QMessageBox
 )
 
 from AnyQt.QtGui import (
@@ -774,9 +774,25 @@ def __on_installer_error(self, command, pkg, retcode, output):
         self.reject()
 
     def __on_installer_finished(self):
-        message = "Please restart Orange for changes to take effect."
-        message_information(message, parent=self)
-        self.accept()
+
+        def message_restart(parent):
+            icon = QMessageBox.Information
+            buttons = QMessageBox.Ok | QMessageBox.Cancel
+            title = 'Information'
+            text = 'A restart of the application is necessary for the ' \
+                   'changes to take effect.'
+
+            msg_box = QMessageBox(icon, title, text, buttons, parent)
+            msg_box.setDefaultButton(QMessageBox.Ok)
+            msg_box.button(QMessageBox.Ok).setText('Restart now')
+            msg_box.button(QMessageBox.Cancel).setText('Restart later')
+            return msg_box.exec_()
+
+        if QMessageBox.Ok == message_restart(self):
+            self.accept()
+            self.parent().close()
+        else:
+            self.reject()
 
 
 def list_available_versions():