Added support for current_window setter.

changes/1887.feature.rst

@@ -0,0 +1 @@
+An API for setting a window into active focus was added.

cocoa/src/toga_cocoa/app.py

@@ -366,9 +366,12 @@ def show_about_dialog(self):
     def exit(self):
         self.loop.stop()
 
-    def current_window(self):
+    def get_current_window(self):
         return self.native.keyWindow
 
+    def set_current_window(self, window):
+        window._impl.native.makeKeyAndOrderFront(window._impl.native)
+
     def enter_full_screen(self, windows):
         # If we're already in full screen mode, exit so that
         # we can re-assign windows to screens.

core/src/toga/app.py

@@ -515,7 +515,12 @@ def main_window(self, window):
     @property
     def current_window(self):
         """Return the currently active content window."""
-        return self._impl.current_window().interface
+        return self._impl.get_current_window().interface
+
+    @current_window.setter
+    def current_window(self, window):
+        """Set a window into current active focus."""
+        self._impl.set_current_window(window)
 
     @property
     def is_full_screen(self):

dummy/src/toga_dummy/app.py

@@ -43,8 +43,12 @@ def exit(self):
         self._action("exit")
 
     @not_required_on("mobile")
-    def current_window(self):
-        self._action("current_window")
+    def get_current_window(self):
+        self._action("get_current_window")
+
+    @not_required_on("mobile")
+    def set_current_window(self):
+        self._action("set_current_window")
 
     @not_required_on("mobile")
     def enter_full_screen(self, windows):

examples/window/window/app.py

@@ -1,3 +1,4 @@
+import asyncio
 from datetime import datetime
 
 import toga
@@ -68,6 +69,12 @@ def do_new_windows(self, widget, **kwargs):
         self.app.windows += no_close_handler_window
         no_close_handler_window.show()
 
+    async def do_current_window_cycling(self, widget, **kwargs):
+        for window in self.windows:
+            self.current_window = window
+            self.label.text = f"Current window is {self.current_window.id}"
+            await asyncio.sleep(1)
+
     def do_report(self, widget, **kwargs):
         self.label.text = (
             f"Window {self.main_window.title!r} "
@@ -136,6 +143,11 @@ def startup(self):
         btn_do_new_windows = toga.Button(
             "Create Window", on_press=self.do_new_windows, style=btn_style
         )
+        btn_do_current_window_cycling = toga.Button(
+            "Cycle between windows",
+            on_press=self.do_current_window_cycling,
+            style=btn_style,
+        )
         btn_do_report = toga.Button("Report", on_press=self.do_report, style=btn_style)
         btn_change_content = toga.Button(
             "Change content", on_press=self.do_next_content, style=btn_style
@@ -152,6 +164,7 @@ def startup(self):
                 btn_do_full_screen,
                 btn_do_title,
                 btn_do_new_windows,
+                btn_do_current_window_cycling,
                 btn_do_report,
                 btn_change_content,
                 btn_hide,

gtk/src/toga_gtk/app.py

@@ -224,9 +224,12 @@ def exit(self):
     def set_on_exit(self, value):
         pass
 
-    def current_window(self):
+    def get_current_window(self):
         return self.native.get_active_window()._impl
 
+    def set_current_window(self, window):
+        window.native.present()
+
     def enter_full_screen(self, windows):
         for window in windows:
             window._impl.set_full_screen(True)

web/src/toga_web/app.py

@@ -179,8 +179,11 @@ def show_dialog(promise):
     def exit(self):
         pass
 
-    def current_window(self):
-        self.interface.factory.not_implemented("App.current_window()")
+    def get_current_window(self):
+        self.interface.factory.not_implemented("App.get_current_window()")
+
+    def set_current_window(self):
+        self.interface.factory.not_implemented("App.set_current_window()")
 
     def enter_full_screen(self, windows):
         self.interface.factory.not_implemented("App.enter_full_screen()")

winforms/src/toga_winforms/app.py

@@ -289,10 +289,12 @@ def exit(self):
     def set_main_window(self, window):
         self.app_context.MainForm = window._impl.native
 
-    @property
-    def current_window(self):
+    def get_current_window(self):
         return WinForms.Form.ActiveForm._impl
 
+    def set_current_window(self, window):
+        window._impl.native.Activate()
+
     def enter_full_screen(self, windows):
         for window in windows:
             window._impl.set_full_screen(True)