diff --git a/mal_gui/app.py b/mal_gui/app.py
index 358dd3b..f3ecd77 100644
--- a/mal_gui/app.py
+++ b/mal_gui/app.py
@@ -53,7 +53,7 @@ def __init__(self, parent=None):
         os.makedirs(os.path.dirname(self.config_file_path), exist_ok=True)
 
         self.config = configparser.ConfigParser()
-        self.config.read(self.config_file_path)
+        self.config.read(self.config_file_path, encoding="utf-8")
         self.selected_lang_file = self.config.get(
             "Settings", "langFilePath", fallback=None
         )
diff --git a/mal_gui/connection_dialog.py b/mal_gui/connection_dialog.py
index 1efe2e4..1225f24 100644
--- a/mal_gui/connection_dialog.py
+++ b/mal_gui/connection_dialog.py
@@ -65,9 +65,8 @@ def __init__(
         for fieldname, association in possible_assocs.items():
             field = association.get_field(fieldname)
 
-            # If assoc ends with end_assets type, give that assoc
-            # as option in list widget
-            if field.asset == self.end_asset.lg_asset:
+            # Association endpoints also accept subassets of their declared type.
+            if self.end_asset.lg_asset.is_subasset_of(field.asset):
                 assoc_list_item = QListWidgetItem(
                     self.start_asset.name
                     + "."
@@ -91,6 +90,7 @@ def __init__(
         self.ok_button = QPushButton("OK")
         self.ok_button.clicked.connect(self.ok_button_clicked)
         self.ok_button.setSizePolicy(QSizePolicy.Expanding, QSizePolicy.Fixed)
+        self.ok_button.setEnabled(self.association_list_widget.count() > 0)
         button_layout.addWidget(self.ok_button)
 
         self.cancel_button = QPushButton("Cancel")
@@ -112,15 +112,16 @@ def filter_items(self, text):
 
     def ok_button_clicked(self):
         selected_item = self.association_list_widget.currentItem()
+        if selected_item is None:
+            return
 
-        if selected_item:
-            data = selected_item.data(Qt.UserRole)
+        data = selected_item.data(Qt.UserRole)
 
-            from_asset: ModelAsset = data.get("from")
-            to_asset: ModelAsset = data.get("to")
-            self.field_name: str = data.get("fieldname")
+        from_asset: ModelAsset = data.get("from")
+        to_asset: ModelAsset = data.get("to")
+        self.field_name: str = data.get("fieldname")
 
-            print(f"{from_asset}.{self.field_name} = {to_asset} chosen")
+        print(f"{from_asset}.{self.field_name} = {to_asset} chosen")
 
         self.accept()
 
diff --git a/tests/test_connection_dialog.py b/tests/test_connection_dialog.py
new file mode 100644
index 0000000..b51a1e5
--- /dev/null
+++ b/tests/test_connection_dialog.py
@@ -0,0 +1,86 @@
+from types import SimpleNamespace
+
+import pytest
+from PySide6.QtCore import Qt
+from PySide6.QtWidgets import QDialog
+
+from maltoolbox.language import LanguageGraphAsset, LanguageGraphAssociation
+from maltoolbox.language.language_graph_assoc import (
+    LanguageGraphAssociationField,
+    link_association_to_assets,
+)
+from maltoolbox.model import ModelAsset
+
+from mal_gui.connection_dialog import AssociationConnectionDialog
+
+
+@pytest.fixture
+def machine_execution_assets(app):
+    machine = LanguageGraphAsset("Machine")
+    infotainment = LanguageGraphAsset("InfotainmentSystem", own_super_asset=machine)
+    application = LanguageGraphAsset("VehicularApplication")
+    operating_system = LanguageGraphAsset(
+        "OperatingSystem", own_super_asset=application
+    )
+
+    association = LanguageGraphAssociation(
+        name="machineExecution",
+        left_field=LanguageGraphAssociationField(machine, "hostMachine", 0, 1),
+        right_field=LanguageGraphAssociationField(
+            application, "machineExecutedApps", 0, 0
+        ),
+    )
+    link_association_to_assets(association, machine, application)
+
+    return {
+        asset.name: ModelAsset(asset.name, asset_id, asset)
+        for asset_id, asset in enumerate(
+            (machine, infotainment, application, operating_system)
+        )
+    }
+
+
+def make_dialog(start_asset, end_asset):
+    start_item = SimpleNamespace(asset=start_asset, asset_type=start_asset.type)
+    end_item = SimpleNamespace(asset=end_asset, asset_type=end_asset.type)
+    return AssociationConnectionDialog(start_item, end_item, None, None)
+
+
+@pytest.mark.parametrize(
+    ("start_type", "end_type", "expected_fieldname"),
+    [
+        ("InfotainmentSystem", "OperatingSystem", "machineExecutedApps"),
+        ("OperatingSystem", "InfotainmentSystem", "hostMachine"),
+        ("Machine", "VehicularApplication", "machineExecutedApps"),
+    ],
+)
+def test_inherited_endpoint_types_are_available(
+    machine_execution_assets, start_type, end_type, expected_fieldname
+):
+    start_asset = machine_execution_assets[start_type]
+    end_asset = machine_execution_assets[end_type]
+    dialog = make_dialog(start_asset, end_asset)
+
+    assert dialog.association_list_widget.count() == 1
+    assert dialog.ok_button.isEnabled()
+    selected_item = dialog.association_list_widget.currentItem()
+    assert selected_item.data(Qt.UserRole)["fieldname"] == expected_fieldname
+
+    dialog.ok_button_clicked()
+    assert dialog.result() == QDialog.Accepted
+    assert dialog.field_name == expected_fieldname
+
+    start_asset.add_associated_assets(expected_fieldname, {end_asset})
+    assert end_asset in start_asset.associated_assets[expected_fieldname]
+
+
+def test_empty_selection_cannot_be_accepted(machine_execution_assets):
+    unrelated_asset = ModelAsset("Unrelated", 4, LanguageGraphAsset("Unrelated"))
+    dialog = make_dialog(machine_execution_assets["Machine"], unrelated_asset)
+
+    assert dialog.association_list_widget.count() == 0
+    assert not dialog.ok_button.isEnabled()
+
+    dialog.ok_button_clicked()
+    assert dialog.result() != QDialog.Accepted
+    assert dialog.field_name is None