Add Last System.Drawing Documentation for .NET 9 (#10490)

Author: lonitra

xml/System.Drawing.Imaging.Effects/Effect.xml

@@ -65,8 +65,9 @@
         <Parameter Name="disposing" Type="System.Boolean" />
       </Parameters>
       <Docs>
-        <param name="disposing">To be added.</param>
-        <summary>To be added.</summary>
+        <param name="disposing">
+          <see langword="true" /> to release both managed and unmanaged resources; <see langword="false" /> to release only unmanaged resources.</param>
+        <summary>Releases the unmanaged resources used by the <see cref="T:System.Drawing.Imaging.Effects.Effect" /> and optionally releases the managed resources.</summary>
         <remarks>To be added.</remarks>
       </Docs>
     </Member>

xml/System.Drawing/SystemColors.xml

@@ -1344,9 +1344,12 @@
         <ReturnType>System.Boolean</ReturnType>
       </ReturnValue>
       <Docs>
-        <summary>To be added.</summary>
-        <value>To be added.</value>
-        <remarks>To be added.</remarks>
+        <summary>Gets or sets a value that indicates whether the alternative color set is used.</summary>
+        <value>When <see langword="true"/>, system <see cref="T:System.Drawing.KnownColor"/> values will return the alternative color set (as returned by <see cref="T:System.Drawing.SystemColors"/> statics or <see cref="M:System.Drawing.Color.FromKnownColor(System.Drawing.KnownColor)"/>). This is currently "dark mode" variants of the system colors.</value>
+        <remarks>
+          <para><see cref="T:System.Drawing.KnownColor"/> <see cref="T:System.Drawing.Color"/> values are always looked up every time you use them and do not retain any other context. As such, existing <see cref="T:System.Drawing.Color"/> values will change when this property is set.</para>
+          <para>On Windows, system <see cref="T:System.Drawing.KnownColor"/> values always return the current Windows color when the OS has a high contrast theme enabled.</para>
+        </remarks>
       </Docs>
     </Member>
     <Member MemberName="Window">

xml/ns-System.Drawing.Imaging.Effects.xml

@@ -1,6 +1,6 @@
 <Namespace Name="System.Drawing.Imaging.Effects">
   <Docs>
-    <summary>To be added.</summary>
+    <summary>Provides functionality for adding effects to images.</summary>
     <remarks>To be added.</remarks>
   </Docs>
 </Namespace>