add remaining system drawing documentation

Author: lonitra

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

@@ -47,12 +47,12 @@
       </Docs>
     </Member>
     <Member MemberName="Dispose">
-      <MemberSignature Language="C#" Value="public virtual void Dispose (bool disposing);" />
-      <MemberSignature Language="ILAsm" Value=".method public hidebysig newslot virtual instance void Dispose(bool disposing) cil managed" />
+      <MemberSignature Language="C#" Value="protected virtual void Dispose (bool disposing);" />
+      <MemberSignature Language="ILAsm" Value=".method familyinstance hidebysig newslot virtual instance void Dispose(bool disposing) cil managed" />
       <MemberSignature Language="DocId" Value="M:System.Drawing.Imaging.Effects.Effect.Dispose(System.Boolean)" />
-      <MemberSignature Language="VB.NET" Value="Public Overridable Sub Dispose (disposing As Boolean)" />
+      <MemberSignature Language="VB.NET" Value="Protected Overridable Sub Dispose (disposing As Boolean)" />
       <MemberSignature Language="F#" Value="abstract member Dispose : bool -&gt; unit&#xA;override this.Dispose : bool -&gt; unit" Usage="effect.Dispose disposing" />
-      <MemberSignature Language="C++ CLI" Value="public:&#xA; virtual void Dispose(bool disposing);" />
+      <MemberSignature Language="C++ CLI" Value="protected:&#xA; virtual void Dispose(bool disposing);" />
       <MemberType>Method</MemberType>
       <AssemblyInfo>
         <AssemblyName>System.Drawing.Common</AssemblyName>
@@ -65,8 +65,8 @@
         <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"/> if managed resources should be disposed; otherwise, <see langword="false"/>.</param>
+        <summary>Releases the resources that are used by the object.</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 whether the alternative color set is used.</summary>
+        <value>When <see langword="true"/>, system <see cref="KnownColor"/> values will return the alternative color set (as returned by <see cref="SystemColors"/> statics or <see cref="Color.FromKnownColor(KnownColor)"/>). This is currently "dark mode" variants of the system colors.</value>
+        <remarks>
+          <para><see cref="KnownColor"/> <see cref="Color"/> values are always looked up every time you use them and do not retain any other context. As such, existing <see cref="Color"/> values will change when this property is set.</para>
+          <para>On Windows, system <see cref="KnownColor"/> values will 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>