WIP: GTK implementation.

gtk/src/toga_gtk/widgets/selection.py

@@ -10,11 +10,20 @@ def create(self):
         self.native.connect("changed", self.gtk_on_select)
 
     def gtk_on_select(self, widget):
-        if self.interface.on_select:
-            self.interface.on_select(widget)
+        self.interface.on_select(None)
 
-    def remove_all_items(self):
+    def change_source(self, source):
         self.native.remove_all()
+        for item in source:
+            self.native.append_text(self.interface._title_for_item(item))
+        self.interface.on_change(None)
+
+        # Gtk.ComboBox does not select the first item by default
+        try:
+            item = source[0]
+            self.select_item(0, None)
+        except IndexError:
+            pass
 
     def add_item(self, item):
         self.native.append_text(item)
@@ -23,19 +32,33 @@ def add_item(self, item):
         if not self.get_selected_item():
             self.select_item(item)
 
-    def select_item(self, item):
-        self.native.set_active(self.interface.items.index(item))
+    def change(self, item):
+        index = self.interface._items.index(item)
+        # Insert a new entry at the same index,
+        # then delete the old entry (at the increased index)
+        self.insert(index, self.interface._title_for_item(item))
+        self.remove(index + 1)
+
+    def insert(self, index, item):
+        self.native.insert_text(index, self.interface._title_for_item(item))
+
+    def remove(self, index, item):
+        self.native.remove(index)
+
+    def clear(self):
+        self.native.remove_all()
+        self.interface.on_select(None)
+
+    def select_item(self, index, item):
+        self.native.set_active(index)
+        self.interface.on_select(None)
 
     def get_selected_item(self):
-        return self.native.get_active_text()
+        return self.interface.items[self.native.get_active()]
 
     def rehint(self):
-        # width = self.native.get_preferred_width()
+        width = self.native.get_preferred_width()
         height = self.native.get_preferred_height()
 
-        self.interface.intrinsic.width = at_least(self.interface._MIN_WIDTH)
+        self.interface.intrinsic.width = at_least(max(self.interface._MIN_WIDTH, width))
         self.interface.intrinsic.height = height[1]
-
-    def set_on_select(self, handler):
-        # No special handling required
-        pass

gtk/tests_backend/widgets/selection.py

@@ -0,0 +1,34 @@
+from toga_gtk.libs import Gtk
+
+from .base import SimpleProbe
+
+
+class SelectionProbe(SimpleProbe):
+    native_class = Gtk.ComboBoxText
+
+    # @property
+    # def alignment(self):
+    #     xfail("Can't change the alignment of Selection on macOS")
+
+    # @property
+    # def color(self):
+    #     xfail("Can't change the color of Selection on macOS")
+
+    # @property
+    # def font(self):
+    #     xfail("Can't change the font of Selection on macOS")
+
+    # @property
+    # def background_color(self):
+    #     xfail("Can't change the background color of Selection on macOS")
+
+    @property
+    def titles(self):
+        return []
+
+    @property
+    def selected_title(self):
+        return self.native.get_active_text()
+
+    async def select_item(self):
+        pass