优化更新代码，添加界面功能并整合

WPFluent/Interop/WinDef/RECT.cs

@@ -0,0 +1,26 @@
+using System.Runtime.InteropServices;
+
+namespace WPFluent.Interop.WinDef;
+
+[StructLayout(LayoutKind.Sequential)]
+public struct RECT(int left, int top, int right, int bottom)
+{
+    public int Left = left;
+    public int Top = top;
+    public int Right = right;
+    public int Bottom = bottom;
+
+    public int Width => Right - Left;
+
+    public int Height => Bottom - Top;
+
+    public void Offset(int dx, int dy)
+    {
+        Left += dx;
+        Top += dy;
+        Right += dx;
+        Bottom += dy;
+    }
+
+    public bool IsEmpty => Left >= Right || Top >= Bottom;
+}