Fix issues based on latest CTI-Testing.

Author: KlausLoeffelmann

src/System.Windows.Forms/System/Windows/Forms/Control.cs

@@ -223,8 +223,8 @@ public unsafe partial class Control :
     private static readonly int s_ambientPropertiesServiceProperty = PropertyStore.CreateKey();
     private static readonly int s_dataContextProperty = PropertyStore.CreateKey();
 
-    private static readonly int s_currentDpiProperty = PropertyStore.CreateKey();
-    private static readonly int s_formerDpiProperty = PropertyStore.CreateKey();
+    private static readonly int s_deviceDpiInternal = PropertyStore.CreateKey();
+    private static readonly int s_originalDeviceDpiInternal = PropertyStore.CreateKey();
 
     private static bool s_needToLoadComCtl = true;
 
@@ -312,7 +312,7 @@ internal Control(bool autoInstallSyncContext) : base()
         // correctly in the PropertyStore, and that it is not set to 0.
         // So, this is available before any Constructor of any inheriting control runs.
         Properties.AddValue(
-            s_currentDpiProperty,
+            s_deviceDpiInternal,
             ScaleHelper.InitialSystemDpi);
 
         _window = new ControlNativeWindow(this);
@@ -424,13 +424,17 @@ public Control(Control? parent, string? text, int left, int top, int width, int
     }
 
     /// <summary>
-    ///  Giving a derived control a chance to initialize its state before the
+    ///  Giving an internally derived control a chance to initialize its state before the
     ///  constructor code runs. If the control needs to access the initial or former
-    ///  DeviceDPI, it can safely access the internal Properties CurrentDpi and
-    ///  FormerDpi at any time.
+    ///  DeviceDPI, it can safely access the internal properties <see cref="DeviceDpiInternal"/>
+    ///  and <see cref="OriginalDeviceDpiInternal"/> to retrieve the DPI value. This method
+    ///  replaces the original internal method <c>InitializeConstantsForInitialDpi</c>.
     /// </summary>
     private protected virtual void InitializeControl()
     {
+        // If you need to provide changed initial DPI values for a derived control,
+        // make sure you set them NOT in the constructor, but provide them here via
+        // the internal properties DeviceDpiInternal and OriginalDeviceDpi.
     }
 
     /// <summary>
@@ -443,33 +447,39 @@ internal int DeviceDpiInternal
         get
         {
             return Properties.GetValueOrDefault(
-                s_currentDpiProperty,
+                s_deviceDpiInternal,
                 ScaleHelper.InitialSystemDpi);
         }
 
         set
         {
             if (value != DeviceDpiInternal)
             {
-                Properties.AddOrRemoveValue(s_currentDpiProperty, value, ScaleHelper.InitialSystemDpi);
+                Properties.AddOrRemoveValue(
+                    s_deviceDpiInternal,
+                    value,
+                    ScaleHelper.InitialSystemDpi);
             }
         }
     }
 
-    internal int FormerDeviceDpi
+    internal int OriginalDeviceDpiInternal
     {
         get
         {
             return Properties.GetValueOrDefault(
-                s_formerDpiProperty,
+                s_originalDeviceDpiInternal,
                 DeviceDpiInternal);
         }
 
         set
         {
-            if (value != FormerDeviceDpi)
+            if (value != OriginalDeviceDpiInternal)
             {
-                Properties.AddOrRemoveValue(s_formerDpiProperty, value, DeviceDpiInternal);
+                Properties.AddOrRemoveValue(
+                    s_originalDeviceDpiInternal,
+                    value,
+                    DeviceDpiInternal);
             }
         }
     }
@@ -5369,9 +5379,9 @@ Site is { } site
         // We would need to get adornments metrics for both (old and new) Dpi in case application is in PerMonitorV2 mode and Dpi changed.
         AdjustWindowRectExForControlDpi(ref adornmentsAfterDpiChange, (WINDOW_STYLE)cp.Style, bMenu: false, (WINDOW_EX_STYLE)cp.ExStyle);
 
-        if (FormerDeviceDpi != DeviceDpiInternal && OsVersion.IsWindows10_1703OrGreater())
+        if (OriginalDeviceDpiInternal != DeviceDpiInternal && OsVersion.IsWindows10_1703OrGreater())
         {
-            AdjustWindowRectExForDpi(ref adornmentsBeforeDpiChange, (WINDOW_STYLE)cp.Style, bMenu: false, (WINDOW_EX_STYLE)cp.ExStyle, FormerDeviceDpi);
+            AdjustWindowRectExForDpi(ref adornmentsBeforeDpiChange, (WINDOW_STYLE)cp.Style, bMenu: false, (WINDOW_EX_STYLE)cp.ExStyle, OriginalDeviceDpiInternal);
         }
         else
         {
@@ -7401,7 +7411,7 @@ void HandleHighDpi()
             int old = DeviceDpiInternal;
             Font localFont = GetCurrentFontAndDpi(out int fontDpi);
 
-            Properties.AddOrRemoveValue(s_currentDpiProperty, (int)PInvoke.GetDpiForWindow(this));
+            Properties.AddOrRemoveValue(s_deviceDpiInternal, (int)PInvoke.GetDpiForWindow(this));
             if (old == DeviceDpiInternal)
             {
                 return;
@@ -9322,9 +9332,9 @@ internal virtual void RecreateHandleCore()
 
             // Note that we need to take DarkMode theming into account at a different point in time
             // than when we create the handle for the first time. The reason is that recreating the handle
-            // usually also recreates the handles of any child controls, and we want to
+            // often also recreates the handles of any child controls, and we want to
             // ensure that the theming is applied to all child controls as well.
-#pragma warning disable WFO5001 // Type is for evaluation purposes only and is subject to change or removal in future updates.
+#pragma warning disable WFO5001
             if (Application.IsDarkModeEnabled
                 && GetStyle(ControlStyles.ApplyThemingImplicitly))
             {
@@ -11511,7 +11521,7 @@ private void WmDpiChangedBeforeParent(ref Message m)
     {
         DefWndProc(ref m);
 
-        Properties.AddOrRemoveValue(s_formerDpiProperty, DeviceDpiInternal);
+        OriginalDeviceDpiInternal = DeviceDpiInternal;
 
         // In order to support tests, will be querying Dpi from the message first.
         int newDeviceDpi = (short)m.WParamInternal.LOWORD;
@@ -11522,14 +11532,14 @@ private void WmDpiChangedBeforeParent(ref Message m)
             newDeviceDpi = (int)PInvoke.GetDpiForWindow(this);
         }
 
-        if (FormerDeviceDpi == newDeviceDpi)
+        if (OriginalDeviceDpiInternal == newDeviceDpi)
         {
             OnDpiChangedBeforeParent(EventArgs.Empty);
             return;
         }
 
         Font localFont = GetCurrentFontAndDpi(out int fontDpi);
-        Properties.AddOrRemoveValue(s_currentDpiProperty, newDeviceDpi);
+        DeviceDpiInternal = newDeviceDpi;
 
         if (fontDpi == DeviceDpiInternal)
         {
@@ -11539,7 +11549,7 @@ private void WmDpiChangedBeforeParent(ref Message m)
 
         // If it is a container control that inherit Font and is scaled by parent, we simply scale Font
         // and wait for OnFontChangedEvent caused by its parent. Otherwise, we scale Font and trigger
-        // 'OnFontChanged' event explicitly. ex: winforms designer in VS.
+        // 'OnFontChanged' event explicitly. ex: WinForms designer in VS.
         ContainerControl? container = this as ContainerControl;
         bool isLocalFontSet = IsFontSet();
 
@@ -11562,7 +11572,7 @@ private void WmDpiChangedBeforeParent(ref Message m)
             // This flag is reset when scaling is done on Container in "OnParentFontChanged".
             container?.IsDpiChangeScalingRequired = true;
 
-            RescaleConstantsForDpi(FormerDeviceDpi, DeviceDpiInternal);
+            RescaleConstantsForDpi(OriginalDeviceDpiInternal, DeviceDpiInternal);
         }
 
         OnDpiChangedBeforeParent(EventArgs.Empty);

src/System.Windows.Forms/System/Windows/Forms/Controls/Buttons/Button.cs

@@ -113,6 +113,7 @@ protected override CreateParams CreateParams
         {
             CreateParams cp = base.CreateParams;
             cp.ClassName = PInvoke.WC_BUTTON;
+
             if (GetStyle(ControlStyles.UserPaint))
             {
                 cp.Style |= PInvoke.BS_OWNERDRAW;
@@ -150,24 +151,27 @@ public virtual DialogResult DialogResult
     /// <summary>
     ///  Defines, whether the control is owner-drawn. Based on this,
     ///  the UserPaint flags get set, which in turn makes it later
-    ///  a Win32 controls, which we wrap (OwnerDraw == false) or if we
-    ///  draw ourselves. If the user wants to opt out of DarkMode, we cannot
-    ///  force System-Painting for FlatStyle.Standard, so we need to know here
-    ///  and now.
+    ///  a Win32 controls, which we wrap (OwnerDraw == false) or not, and then
+    ///  we draw ourselves. If the user wants to opt out of DarkMode, we can no
+    ///  longer force (wrapping) System-Painting for FlatStyle.Standard, and we
+    ///  need this then also here and now, before CreateParams is called.
     /// </summary>
     private protected override bool OwnerDraw
     {
         get
         {
             if (Application.IsDarkModeEnabled
+
                 // The SystemRenderer cannot render images. So, we flip to our
-                // own DarkMode renderer, if we need to render images, except if
-                && GetStyle(ControlStyles.ApplyThemingImplicitly)
-                // the user wants to opt out of implicit DarkMode rendering.
+                // own DarkMode renderer, if we need to render images, except if...
                 && Image is null
-                // And this only counts for FlatStyle.Standard. For the rest,
-                // we're using specific renderers, which check themselves, if
-                // they need to apply Light- or DarkMode.
+
+                // ...the user wants to opt out of implicit DarkMode rendering.
+                && GetStyle(ControlStyles.ApplyThemingImplicitly)
+
+                // And all of this only counts for FlatStyle.Standard. For the
+                // rest, we're using specific renderers anyway, which check
+                // themselves on demand, if they need to apply Light- or DarkMode.
                 && FlatStyle == FlatStyle.Standard)
             {
                 return false;

src/System.Windows.Forms/System/Windows/Forms/Controls/Buttons/ButtonBase.cs

@@ -68,14 +68,16 @@ protected ButtonBase()
                 | ControlStyles.Opaque
                 | ControlStyles.ResizeRedraw
                 | ControlStyles.OptimizedDoubleBuffer
-                // We gain about 2% in painting by avoiding extra GetWindowText calls
                 | ControlStyles.CacheText
                 | ControlStyles.StandardClick,
             true);
 
         // This class overrides GetPreferredSizeCore, let Control automatically cache the result
         SetExtendedState(ExtendedStates.UserPreferredSizeCache, true);
 
+        // Be aware that OwnerDraw is effective calling CreateParams which in turn can be overwritten
+        // by derived classes. So, it's important to set certain flags already in CreateParams -
+        // setting them in the derived control's constructor would already be too late!
         SetStyle(ControlStyles.UserMouse | ControlStyles.UserPaint, OwnerDraw);
 
         SetFlag(FlagUseMnemonic, true);
@@ -259,6 +261,7 @@ protected override CreateParams CreateParams
 #pragma warning restore WFO5001 // Type is for evaluation purposes only and is subject to change or removal in future updates. Suppress this diagnostic to proceed.
 
             CreateParams cp = base.CreateParams;
+
             if (!OwnerDraw)
             {
                 // WS_EX_RIGHT overrides the BS_XXXX alignment styles

src/System.Windows.Forms/System/Windows/Forms/Controls/ListBoxes/ListBox.cs

@@ -89,7 +89,7 @@ public partial class ListBox : ListControl
     private int _itemsCount;
 
     /// <summary>
-    ///  This value stores the array of custom tabstops in the listBox. the array should be populated by
+    ///  This value stores the array of custom TabStops in the listBox. the array should be populated by
     ///  integers in a ascending order.
     /// </summary>
     private IntegerCollection? _customTabOffsets;
@@ -264,6 +264,10 @@ protected override CreateParams CreateParams
     {
         get
         {
+#pragma warning disable WFO5001
+            SetStyle(ControlStyles.ApplyThemingImplicitly, true);
+#pragma warning restore WFO5001
+
             CreateParams cp = base.CreateParams;
             cp.ClassName = PInvoke.WC_LISTBOX;
 

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

@@ -2593,7 +2593,7 @@ private void OnLayoutInternal(bool dividerOnly)
         {
             // PropertyGrid does a special handling on scaling and positioning its
             // child controls. These are not scaled by their parent when Dpi/Font change.
-            if (FormerDeviceDpi != DeviceDpiInternal)
+            if (OriginalDeviceDpiInternal != DeviceDpiInternal)
             {
                 RescaleConstants();
                 SetupToolbar(fullRebuild: true);

src/System.Windows.Forms/System/Windows/Forms/Controls/TextBox/TextBoxBase.cs

@@ -269,6 +269,7 @@ public override bool AutoSize
         }
     }
 
+#pragma warning disable WFO5001 // Type is for evaluation purposes only and is subject to change or removal in future updates. Suppress this diagnostic to proceed.
     /// <summary>
     ///  Gets or sets the background color of the control.
     /// </summary>
@@ -283,17 +284,22 @@ public override Color BackColor
             {
                 return base.BackColor;
             }
-            else if (ReadOnly)
-            {
-                return SystemColors.Control;
-            }
             else
             {
-                return SystemColors.Window;
+                return ReadOnly
+
+                    // If we're ReadOnly and in DarkMode, we are using a different background color.
+                    ? Application.IsDarkModeEnabled
+                        && GetStyle(ControlStyles.ApplyThemingImplicitly)
+                            ? SystemColors.ControlLight
+                            : SystemColors.Control
+                    : SystemColors.Window;
             }
         }
+
         set => base.BackColor = value;
     }
+#pragma warning restore WFO5001 // Type is for evaluation purposes only and is subject to change or removal in future updates. Suppress this diagnostic to proceed.
 
     [Browsable(false)]
     [EditorBrowsable(EditorBrowsableState.Never)]
@@ -930,9 +936,11 @@ public bool ReadOnly
             if (_textBoxFlags[s_readOnly] != value)
             {
                 _textBoxFlags[s_readOnly] = value;
+
                 if (IsHandleCreated)
                 {
                     PInvokeCore.SendMessage(this, PInvokeCore.EM_SETREADONLY, (WPARAM)(BOOL)value);
+                    EnsureReadonlyBackgroundColor(value);
                 }
 
                 OnReadOnlyChanged(EventArgs.Empty);
@@ -942,6 +950,19 @@ public bool ReadOnly
         }
     }
 
+#pragma warning disable WFO5001 // Type is for evaluation purposes only and is subject to change or removal in future updates. Suppress this diagnostic to proceed.
+    private void EnsureReadonlyBackgroundColor(bool value)
+    {
+        // If we have no specifically defined back color, we set the back color in case we're in dark mode.
+        if (Application.IsDarkModeEnabled
+            && GetStyle(ControlStyles.ApplyThemingImplicitly))
+        {
+            base.BackColor = value ? SystemColors.ControlLight : SystemColors.Window;
+            Invalidate();
+        }
+    }
+#pragma warning restore WFO5001 // Type is for evaluation purposes only and is subject to change or removal in future updates. Suppress this diagnostic to proceed.
+
     [SRCategory(nameof(SR.CatPropertyChanged))]
     [SRDescription(nameof(SR.TextBoxBaseOnReadOnlyChangedDescr))]
     public event EventHandler? ReadOnlyChanged
@@ -1372,6 +1393,8 @@ protected override void OnHandleCreated(EventArgs e)
             PInvokeCore.SendMessage(this, PInvokeCore.EM_SETMODIFY, (WPARAM)(BOOL)true);
         }
 
+        EnsureReadonlyBackgroundColor(true);
+
         if (_textBoxFlags[s_scrollToCaretOnHandleCreated])
         {
             ScrollToCaret();

src/System.Windows.Forms/System/Windows/Forms/Form.cs

@@ -4516,7 +4516,7 @@ protected virtual void OnDpiChanged(DpiChangedEventArgs e)
         if (e.DeviceDpiNew != e.DeviceDpiOld)
         {
             CommonProperties.xClearAllPreferredSizeCaches(this);
-            FormerDeviceDpi = e.DeviceDpiOld;
+            OriginalDeviceDpiInternal = e.DeviceDpiOld;
 
             // call any additional handlers
             ((DpiChangedEventHandler?)Events[s_dpiChangedEvent])?.Invoke(this, e);