Add ImageList.UseMaskForTransparency for better image transparency

src/System.Windows.Forms/Resources/SR.resx

@@ -3447,6 +3447,9 @@ Stack trace where the illegal operation occurred was:
   <data name="ImageListTransparentColorDescr" xml:space="preserve">
     <value>The color that is treated as transparent.</value>
   </data>
+  <data name="ImageListUseMaskForTransparencyDescr" xml:space="preserve">
+    <value>Gets or sets whether to use a mask for transparency.</value>
+  </data>
   <data name="IndexOutOfRange" xml:space="preserve">
     <value>Index {0} is out of range.</value>
   </data>

src/System.Windows.Forms/System/Windows/Forms/Controls/ImageList/ImageList.ImageCollection.cs

@@ -155,17 +155,34 @@ public Image this[int index]
 
                 try
                 {
-                    HBITMAP hMask = (HBITMAP)ControlPaint.CreateHBitmapTransparencyMask(bitmap);
-                    HBITMAP hBitmap = (HBITMAP)ControlPaint.CreateHBitmapColorMask(bitmap, hMask);
                     bool ok;
-                    try
+                    if (!_owner.UseMaskForTransparency)
                     {
-                        ok = PInvoke.ImageList.Replace(_owner, index, hBitmap, hMask);
+                        HBITMAP hBitmap = (HBITMAP)bitmap.GetHbitmap();
+                        try
+                        {
+                            using var ilHandle = new DeleteObjectSafeHandle(_owner.Handle, ownsHandle: false);
+                            ok = PInvoke.ImageList_Replace(ilHandle, index, hBitmap, default);
+                        }
+                        finally
+                        {
+                            PInvokeCore.DeleteObject(hBitmap);
+                        }
                     }
-                    finally
+                    else
                     {
-                        PInvokeCore.DeleteObject((HGDIOBJ)hBitmap);
-                        PInvokeCore.DeleteObject((HGDIOBJ)hMask);
+                        HBITMAP hMask = (HBITMAP)ControlPaint.CreateHBitmapTransparencyMask(bitmap);
+                        HBITMAP hBitmap = (HBITMAP)ControlPaint.CreateHBitmapColorMask(bitmap, hMask);
+                        bool ok;
+                        try
+                        {
+                            ok = PInvoke.ImageList.Replace(_owner, index, hBitmap, hMask);
+                        }
+                        finally
+                        {
+                            PInvokeCore.DeleteObject((HGDIOBJ)hBitmap);
+                            PInvokeCore.DeleteObject((HGDIOBJ)hMask);
+                        }
                     }
 
                     if (!ok)

src/System.Windows.Forms/System/Windows/Forms/Controls/ImageList/ImageList.cs

@@ -261,6 +261,13 @@ public ImageListStreamer? ImageStream
 
     private bool UseTransparentColor => TransparentColor.A > 0;
 
+    /// <summary>
+    ///  Gets or sets whether to use a mask for transparency.
+    /// </summary>
+    [SRCategory(nameof(SR.CatBehavior))]
+    [SRDescription(nameof(SR.ImageListUseMaskForTransparencyDescr))]
+    public bool UseMaskForTransparency { get; set; } = true;
+
     [Browsable(false)]
     [EditorBrowsable(EditorBrowsableState.Advanced)]
     [SRDescription(nameof(SR.ImageListOnRecreateHandleDescr))]
@@ -370,21 +377,37 @@ private int AddToHandle(Bitmap bitmap)
     {
         Debug.Assert(HandleCreated, "Calling AddToHandle when there is no handle");
 
-        // Calls GDI to create Bitmap.
-        HBITMAP hMask = (HBITMAP)ControlPaint.CreateHBitmapTransparencyMask(bitmap);
-
-        // Calls GDI+ to create Bitmap
-        HBITMAP hBitmap = (HBITMAP)ControlPaint.CreateHBitmapColorMask(bitmap, (IntPtr)hMask);
-
         int index;
-        try
+        if (!UseMaskForTransparency)
         {
-            index = PInvoke.ImageList.Add(this, hBitmap, hMask);
+            HBITMAP hBitmap = (HBITMAP)bitmap.GetHbitmap();
+            try
+            {
+                using var ilHandle = new DeleteObjectSafeHandle(Handle, ownsHandle: false);
+                index = PInvoke.ImageList_Add(ilHandle, hBitmap, default);
+            }
+            finally
+            {
+                PInvokeCore.DeleteObject(hBitmap);
+            }
         }
-        finally
+        else
         {
-            PInvokeCore.DeleteObject(hBitmap);
-            PInvokeCore.DeleteObject(hMask);
+            // Calls GDI to create Bitmap.
+            HBITMAP hMask = (HBITMAP)ControlPaint.CreateHBitmapTransparencyMask(bitmap);
+
+            // Calls GDI+ to create Bitmap
+            HBITMAP hBitmap = (HBITMAP)ControlPaint.CreateHBitmapColorMask(bitmap, (IntPtr)hMask);
+
+            try
+            {
+                index = PInvoke.ImageList.Add(this, hBitmap, hMask);
+            }
+            finally
+            {
+                PInvokeCore.DeleteObject(hBitmap);
+                PInvokeCore.DeleteObject(hMask);
+            }
         }
 
         return index == -1 ? throw new InvalidOperationException(SR.ImageListAddFailed) : index;