kivy: pass show_max as parameter

gui/kivy/main_window.py

@@ -731,10 +731,8 @@ class ElectrumWindow(App):
         popup.tx_hash = tx_hash
         popup.open()
 
-    def amount_dialog(self, label, callback):
+    def amount_dialog(self, label, callback, show_max):
         popup = Builder.load_file('gui/kivy/uix/ui_screens/amount.kv')
-        # Hide max_button
-        show_max = False
         but_max = popup.ids.but_max
         if not show_max:
             but_max.disabled = True

gui/kivy/uix/ui_screens/receive.kv

@@ -52,7 +52,7 @@ ReceiveScreen:
                     halign: 'left'
                     size_hint: 0.5, None
                     height: '38dp'
-                    on_release: app.amount_dialog(amount, receive_screen.parent.update_qr)
+                    on_release: app.amount_dialog(amount, receive_screen.parent.update_qr, False)
                     background_color: 0, 0, 0, 0
             CardSeparator:
                 opacity: message_selection.opacity

gui/kivy/uix/ui_screens/send.kv

@@ -109,7 +109,7 @@ SendScreen:
                     halign: 'left'
                     size_hint: 0.5, None
                     height: '38dp'
-                    on_release: app.amount_dialog(self, None)
+                    on_release: app.amount_dialog(self, None, True)
                     background_color: .238, .585, .878, 0
             CardSeparator:
                 opacity: message_selection.opacity