Fixes for update fiat rate after change of current wallet type. Fixes for change amount for btc transactions. Changed displaying of balance for btc wallet. General fixes.

lib/store/app_store.dart

@@ -26,4 +26,10 @@ abstract class AppStoreBase with Store {
   SettingsStore settingsStore;
 
   NodeListStore nodeListStore;
+
+  @action
+  void changeCurrentWallet(WalletBase wallet) {
+    this.wallet?.close();
+    this.wallet = wallet;
+  }
 }

lib/store/dashboard/fiat_conversion_store.dart

@@ -1,13 +1,13 @@
+import 'package:cake_wallet/entities/crypto_currency.dart';
 import 'package:mobx/mobx.dart';
 
 part 'fiat_conversion_store.g.dart';
 
-class FiatConversionStore = FiatConversionStoreBase
-    with _$FiatConversionStore;
+class FiatConversionStore = FiatConversionStoreBase with _$FiatConversionStore;
 
 abstract class FiatConversionStoreBase with Store {
-  FiatConversionStoreBase() : price = 0.0;
+  FiatConversionStoreBase() : prices = ObservableMap<CryptoCurrency, double>();
 
   @observable
-  double price;
+  ObservableMap<CryptoCurrency, double> prices;
 }

lib/store/settings_store.dart

@@ -43,7 +43,6 @@ abstract class SettingsStoreBase with Store {
     isDarkTheme = initialDarkTheme;
     pinCodeLength = initialPinLength;
     languageCode = initialLanguageCode;
-    currentNode = nodes[WalletType.monero];
     this.nodes = ObservableMap<WalletType, Node>.of(nodes);
     _sharedPreferences = sharedPreferences;
 
@@ -80,13 +79,14 @@ abstract class SettingsStoreBase with Store {
         (int pinLength) => sharedPreferences.setInt(
             PreferencesKey.currentPinLength, pinLength));
 
-    reaction((_) => currentNode,
-        (Node node) => _saveCurrentNode(node, WalletType.monero));
-
     reaction(
         (_) => languageCode,
         (String languageCode) => sharedPreferences.setString(
             PreferencesKey.currentLanguageCode, languageCode));
+
+    this
+        .nodes
+        .observe((change) => _saveCurrentNode(change.newValue, change.key));
   }
 
   static const defaultPinLength = 4;
@@ -116,9 +116,6 @@ abstract class SettingsStoreBase with Store {
   @observable
   int pinCodeLength;
 
-  @observable
-  Node currentNode;
-
   @computed
   ThemeData get theme => isDarkTheme ? Themes.darkTheme : Themes.lightTheme;