Merge pull request #7755 from AvaloniaUI/fixes/win32-can-resize

Fixes/win32 can resize

src/Windows/Avalonia.Win32/WindowImpl.CustomCaptionProc.cs

@@ -23,16 +23,10 @@ namespace Avalonia.Win32
             AdjustWindowRectEx(ref rcFrame, (uint)(WindowStyles.WS_OVERLAPPEDWINDOW & ~WindowStyles.WS_CAPTION), false, 0);
 
             var borderThickness = new RECT();
-            if (GetStyle().HasAllFlags(WindowStyles.WS_THICKFRAME))
-            {
-                AdjustWindowRectEx(ref borderThickness, (uint)(GetStyle()), false, 0);
-                borderThickness.left *= -1;
-                borderThickness.top *= -1;
-            }
-            else if (GetStyle().HasAllFlags(WindowStyles.WS_BORDER))
-            {
-                borderThickness = new RECT { bottom = 1, left = 1, right = 1, top = 1 };
-            }
+            
+            AdjustWindowRectEx(ref borderThickness, (uint)GetStyle(), false, 0);
+            borderThickness.left *= -1;
+            borderThickness.top *= -1;
 
             if (_extendTitleBarHint >= 0)
             {

src/Windows/Avalonia.Win32/WindowImpl.cs

@@ -648,13 +648,16 @@ namespace Avalonia.Win32
 
         public void BeginResizeDrag(WindowEdge edge, PointerPressedEventArgs e)
         {
+            if (_windowProperties.IsResizable)
+            {
 #if USE_MANAGED_DRAG
-            _managedDrag.BeginResizeDrag(edge, ScreenToClient(MouseDevice.Position.ToPoint(_scaling)));
+                _managedDrag.BeginResizeDrag(edge, ScreenToClient(MouseDevice.Position.ToPoint(_scaling)));
 #else
-            _mouseDevice.Capture(null);
-            DefWindowProc(_hwnd, (int)WindowsMessage.WM_NCLBUTTONDOWN,
-                new IntPtr((int)s_edgeLookup[edge]), IntPtr.Zero);
+                _mouseDevice.Capture(null);
+                DefWindowProc(_hwnd, (int)WindowsMessage.WM_NCLBUTTONDOWN,
+                    new IntPtr((int)s_edgeLookup[edge]), IntPtr.Zero);
 #endif
+            }
         }
 
         public void SetTitle(string title)