fix virtualkeyboard bug

plugins/virtualkeyboard.py

@@ -1,10 +1,10 @@
 from PyQt4.QtGui import *
 from electrum.plugins import BasePlugin, hook
 from electrum.i18n import _
+import random
 
 class Plugin(BasePlugin):
 
-
     def fullname(self):
         return 'Virtual Keyboard'
 
@@ -24,17 +24,16 @@ class Plugin(BasePlugin):
         vkb_button.clicked.connect(lambda: self.toggle_vkb(grid, pw))
         grid.addWidget(vkb_button, pos, 2)
         self.kb_pos = 2
-
+        self.vkb = None
 
     def toggle_vkb(self, grid, pw):
-        if self.vkb: grid.removeItem(self.vkb)
+        if self.vkb:
+            grid.removeItem(self.vkb)
         self.vkb = self.virtual_keyboard(self.vkb_index, pw)
         grid.addLayout(self.vkb, self.kb_pos, 0, 1, 3)
         self.vkb_index += 1
 
-
     def virtual_keyboard(self, i, pw):
-        import random
         i = i%3
         if i == 0:
             chars = 'abcdefghijklmnopqrstuvwxyz '