fix cubetree init crash.

Disp/DemoStl.cs

@@ -1,6 +1,7 @@
-using Hi.Geom;
+using Hi.Disp;
+using Hi.Geom;
+using Hi.WpfPlus.Disp;
 using System;
-using Hi.Disp;
 
 namespace Sample.Disp
 {
@@ -41,7 +42,7 @@ namespace Sample.Disp
 			Console.WriteLine("bouindingbox.Min: " + bouindingbox.Min);
 			Console.WriteLine("bouindingbox.Max: " + bouindingbox.Max);
 			Console.WriteLine("bouindingbox.Center: " + bouindingbox.Center);
-			DispUtil.CallRenderingFrame("DemoForm", stl.ToFaceDrawing());
+			DispFrameUtil.Call("DemoForm", stl.ToFaceDrawing());
 			#endregion
 		}
 

Disp/DemoUtil.cs

@@ -4,8 +4,8 @@ using Hi.Licenses;
 using Hi.WpfPlus.Disp;
 using System.Windows;
 
-namespace Sample.Disp
-{
+namespace Sample.Disp;
+
 /// <summary>
 /// Provides utility functions for running HiAPI display examples in a WPF environment.
 /// Contains helper methods that simplify the setup and execution of WPF applications with HiAPI rendering.
@@ -39,4 +39,3 @@ namespace Sample.Disp
 		});
 	}
 }
-}