Circumvention for SDL2 focus bug

main.py

@@ -26,6 +26,10 @@ from kivymd.uix.dialog import MDDialog
 __version__ = "0.1.5"
 __variant__ = "alpha"
 
+if RNS.vendor.platformutils.get_platform() == "android":
+    from jnius import autoclass
+    from android.runnable import run_on_ui_thread
+
 class SidebandApp(MDApp):
     def __init__(self, **kwargs):
         super().__init__(**kwargs)
@@ -90,12 +94,44 @@ class SidebandApp(MDApp):
         EventLoop.window.bind(on_keyboard=self.keyboard_event)
         EventLoop.window.bind(on_key_down=self.keydown_event)
         
+        # This incredibly hacky hack circumvents a bug in SDL2
+        # that prevents focus from being correctly released from
+        # the software keyboard on Android. Without this the back
+        # button/gesture does not work after the soft-keyboard has
+        # appeared for the first time.
+        if RNS.vendor.platformutils.get_platform() == "android":
+            BIND_CLASSES = ["kivymd.uix.textfield.textfield.MDTextField",]
+            
+            for e in self.root.ids:
+                te = self.root.ids[e]
+                ts = str(te).split(" ")[0].replace("<", "")
+
+                if ts in BIND_CLASSES:
+                    te.bind(focus=self.android_focus_fix)
+                #     RNS.log("Bound "+str(e)+" / "+ts)
+                # else:
+                #     RNS.log("Did not bind "+str(e)+" / "+ts)
+
+                # RNS.log(str(e))
+
         self.root.ids.screen_manager.app = self
         self.root.ids.app_version_info.text = "Sideband v"+__version__+" "+__variant__
         self.open_conversations()
 
         Clock.schedule_interval(self.jobs, 1)
     
+    # Part of the focus hack fix
+    def android_focus_fix(self, sender, val):
+        if not val:
+            @run_on_ui_thread
+            def fix_back_button():
+                activity = autoclass('org.kivy.android.PythonActivity').mActivity
+                activity.onWindowFocusChanged(False)
+                activity.onWindowFocusChanged(True)
+
+            fix_back_button()
+
+
     def keydown_event(self, instance, keyboard, keycode, text, modifiers):
         if len(modifiers) > 0 and modifiers[0] == 'ctrl' and (text == "w" or text == "q"):
             self.quit_action(self)