Refactor Network and Blockchain dialogs in qt and kivy

gui/kivy/uix/dialogs/blockchain_dialog.py

@@ -0,0 +1,63 @@
+from kivy.app import App
+from kivy.factory import Factory
+from kivy.properties import ObjectProperty
+from kivy.lang import Builder
+
+from electrum.i18n import _
+
+Builder.load_string('''
+#:import _ electrum_gui.kivy.i18n._
+
+<BlockchainDialog@Popup>
+    id: popup
+    title: _('Blockchain')
+    size_hint: 1, 1
+    cp_height: 0
+    cp_value: ''
+
+    BoxLayout:
+        orientation: 'vertical'
+        padding: '10dp'
+        spacing: '10dp'
+        TopLabel:
+            height: '48dp'
+            id: bc_height
+            text: _("Verified headers: %d blocks.")% app.num_blocks
+        TopLabel:
+            height: '48dp'
+            id: bc_status
+            text: _("Connected to %d nodes.")% app.num_nodes if app.num_nodes else _("Not connected?")
+        Widget:
+            size_hint: 1, 0.1
+        TopLabel:
+            text: _("Electrum connects to several nodes in order to download block headers and find out the longest blockchain.") + _("This blockchain is used to verify the transactions sent by your transaction server.")
+            font_size: '6pt'
+        Widget:
+            size_hint: 1, 0.1
+        Widget:
+            size_hint: 1, 0.1
+        BoxLayout:
+            orientation: 'horizontal'
+            size_hint: 1, 0.2
+            Button:
+                text: _('Cancel')
+                size_hint: 0.5, None
+                height: '48dp'
+                on_release: popup.dismiss()
+            Button:
+                text: _('OK')
+                size_hint: 0.5, None
+                height: '48dp'
+                on_release:
+                    root.callback(root.cp_height, root.cp_value)
+                    popup.dismiss()
+''')
+
+class BlockchainDialog(Factory.Popup):
+    def __init__(self, network, callback):
+        Factory.Popup.__init__(self)
+        self.network = network
+        self.callback = callback
+        self.is_split = len(self.network.blockchains) > 1
+
+        self.checkpoint_height = network.get_checkpoint()