Regression test for ToolPaneModel deferred-content opt-out

Single assertion guarding the existing IDeferredContentPresentation.DeferContentPresentation
override that keeps tool panes (search, analyzers, debug-steps, …) hot at
startup. Without the opt-out, headless tests can't reach pane descendants
until focus-activation, and the search pane's startup tasks (assembly index
scan etc.) wouldn't kick off until first user interaction.

Assisted-by: Claude:claude-opus-4-7:Claude Code

ILSpy.Tests/MainWindow/ToolPaneDeferredContentTests.cs

@@ -0,0 +1,47 @@
+// Copyright (c) 2026 AlphaSierraPapa for the SharpDevelop Team
+//
+// Permission is hereby granted, free of charge, to any person obtaining a copy of this
+// software and associated documentation files (the "Software"), to deal in the Software
+// without restriction, including without limitation the rights to use, copy, modify, merge,
+// publish, distribute, sublicense, and/or sell copies of the Software, and to permit persons
+// to whom the Software is furnished to do so, subject to the following conditions:
+//
+// The above copyright notice and this permission notice shall be included in all copies or
+// substantial portions of the Software.
+//
+// THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR IMPLIED,
+// INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, FITNESS FOR A PARTICULAR
+// PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE
+// FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR
+// OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER
+// DEALINGS IN THE SOFTWARE.
+
+using AwesomeAssertions;
+
+using Dock.Controls.DeferredContentControl;
+
+using ILSpy.ViewModels;
+
+using NUnit.Framework;
+
+namespace ICSharpCode.ILSpy.Tests;
+
+/// <summary>
+/// Regression guard: <see cref="ToolPaneModel"/> opts out of Dock's deferred content
+/// presentation so panes (search, analyzers, debug steps, etc.) materialise their views
+/// eagerly. Without this, tests can't reach descendants of a pane until it's
+/// focus-activated by the user — and the search-pane's startup tasks (assembly index
+/// scan, etc.) wouldn't kick off until first activation.
+/// </summary>
+[TestFixture]
+public class ToolPaneDeferredContentTests
+{
+	[Test]
+	public void ToolPaneModel_Opts_Out_Of_Dock_Deferred_Content_Presentation()
+	{
+		var sentinel = new TestToolPane();
+		((IDeferredContentPresentation)sentinel).DeferContentPresentation.Should().BeFalse();
+	}
+
+	sealed class TestToolPane : ToolPaneModel { }
+}