Calendar/AddEventDialog: Add a cancel button

Author: https://github.com/david072
Commit: 7df936b660
Pull-request: https://github.com/SerenityOS/serenity/pull/21976
Issue: https://github.com/SerenityOS/serenity/issues/21713
Reviewed-by: https://github.com/ADKaster ✅
Reviewed-by: https://github.com/AtkinsSJ

Userland/Applications/Calendar/AddEventDialog.cpp

@@ -90,6 +90,9 @@ AddEventDialog::AddEventDialog(Core::DateTime date_time, EventManager& event_man
         done(ExecResult::OK);
     };
 
+    auto& cancel_button = *widget->find_descendant_of_type_named<GUI::Button>("cancel_button");
+    cancel_button.on_click = [&](auto) { done(ExecResult::Cancel); };
+
     auto update_starting_input_values = [&, this]() {
         auto hour = starting_hour_input.value();
         auto minute = starting_minute_input.value();

Userland/Applications/Calendar/AddEventDialog.gml

@@ -111,6 +111,12 @@
 
         @GUI::Layout::Spacer {}
 
+        @GUI::Button {
+            name: "cancel_button"
+            text: "Cancel"
+            fixed_size: [80, 20]
+        }
+
         @GUI::Button {
             name: "ok_button"
             text: "OK"