exchange rate plugin: bi-directional conversion

gui/qt/main_window.py

@@ -641,7 +641,7 @@ class ElectrumWindow(QMainWindow):
     def create_send_tab(self):
         w = QWidget()
 
-        grid = QGridLayout(w)
+        self.send_grid = grid = QGridLayout(w)
         grid.setSpacing(8)
         grid.setColumnMinimumWidth(3,300)
         grid.setColumnStretch(5,1)
@@ -694,8 +694,6 @@ class ElectrumWindow(QMainWindow):
                     + _('The amount of fee can be decided freely by the sender. However, transactions with low fees take more time to be processed.') + '\n\n'\
                     + _('A suggested fee is automatically added to this field. You may override it. The suggested fee increases with the size of the transaction.')), 5, 3)
 
-        run_hook('exchange_rate_button', grid)
-
         self.send_button = EnterButton(_("Send"), self.do_send)
         grid.addWidget(self.send_button, 6, 1)