Added Remove VM button

Button added on the basic tab of VM Settings. Button active only when
VM is shutdown; furthermore, requires the user to enter full VM name
to confirm.

qubesmanager/settings.py

@@ -86,6 +86,7 @@ class VMSettingsWindow(Ui_SettingsDialog, QDialog):
         ###### basic tab
         self.__init_basic_tab__()
         self.rename_vm_button.clicked.connect(self.rename_vm)
+        self.delete_vm_button.clicked.connect(self.remove_vm)
 
         ###### advanced tab
         self.__init_advanced_tab__()
@@ -237,6 +238,11 @@ class VMSettingsWindow(Ui_SettingsDialog, QDialog):
         self.vmname.setValidator(QRegExpValidator(QRegExp("[a-zA-Z0-9-]*", Qt.CaseInsensitive), None))
         self.vmname.setEnabled(False)
         self.rename_vm_button.setEnabled(not self.vm.is_running())
+        self.delete_vm_button.setEnabled(not self.vm.is_running())
+
+        if self.vm.is_running():
+            self.delete_vm_button.setText(self.tr('Delete VM '
+                                            '(cannot delete a running VM)'))
 
         if self.vm.qid == 0:
             self.vmlabel.setVisible(False)
@@ -435,6 +441,47 @@ class VMSettingsWindow(Ui_SettingsDialog, QDialog):
 
             self.done(0)
 
+    def _remove_vm(self, t_monitor):
+        try:
+            del self.vm.app.domains[self.vm.name]
+
+        except Exception as ex:
+            t_monitor.set_error_msg(str(ex))
+
+        t_monitor.set_finished()
+
+    def remove_vm(self):
+
+        answer, ok = QInputDialog.getText(self, self.tr('Delete VM')
+            , self.tr('Are you absolutely sure you want to delete this VM? '
+                      '<br \> All VM settings and data will be irrevocably'
+                      ' deleted. <br \> If you are sure, please enter this '
+                      'VM\'s name below.'))
+
+
+        if ok and answer == self.vm.name:
+            t_monitor = thread_monitor.ThreadMonitor()
+            thread = threading.Thread(target=self._remove_vm,
+                                      args=(t_monitor,))
+            thread.daemon = True
+            thread.start()
+
+            while not t_monitor.is_finished():
+                self.qapp.processEvents()
+                time.sleep(0.1)
+
+            if not t_monitor.success:
+                QMessageBox.warning(None,
+                                    self.tr("Error deleting the VM!"),
+                                    self.tr("ERROR: {}").format(
+                                        t_monitor.error_msg))
+
+            self.done(0)
+
+        else:
+            QMessageBox.warning(None, self.tr("Removal cancelled")
+                                , self.tr("The VM will not be removed."))
+
     ######### advanced tab
 
     def __init_advanced_tab__(self):

ui/settingsdlg.ui

@@ -7,7 +7,7 @@
     <x>0</x>
     <y>0</y>
     <width>773</width>
-    <height>573</height>
+    <height>581</height>
    </rect>
   </property>
   <property name="windowTitle">
@@ -29,7 +29,7 @@
         <locale language="English" country="UnitedStates"/>
        </property>
        <property name="currentIndex">
-        <number>2</number>
+        <number>0</number>
        </property>
        <widget class="QWidget" name="basic_tab">
         <property name="locale">
@@ -170,7 +170,7 @@
            </layout>
           </widget>
          </item>
-         <item row="5" column="0">
+         <item row="6" column="0">
           <spacer name="verticalSpacer">
            <property name="orientation">
             <enum>Qt::Vertical</enum>
@@ -373,6 +373,19 @@
            </layout>
           </widget>
          </item>
+         <item row="4" column="1">
+          <widget class="QPushButton" name="delete_vm_button">
+           <property name="styleSheet">
+            <string notr="true">background-color: qlineargradient(spread:pad, x1:1, y1:1, x2:1, y2:0, stop:0 rgba(255, 179, 179, 255), stop:1 rgba(255, 108, 108, 255));
+border-color: rgb(170, 0, 0);
+border-style: solid;
+border-width: 1px;</string>
+           </property>
+           <property name="text">
+            <string>Delete VM</string>
+           </property>
+          </widget>
+         </item>
         </layout>
        </widget>
        <widget class="QWidget" name="advanced_tab">