HidePrefix and PrefixOnly are still effective (#3868)

* HidePrefix and PrefixOnly are still effective

* corrections for 'ModifyString` flag

* added a distinction between effects of these flags on DrawText and MeasureText

* Update xml/System.Windows.Forms/TextFormatFlags.xml

Co-Authored-By: Maira Wenzel <[email protected]>

* Update xml/System.Windows.Forms/TextFormatFlags.xml

Co-Authored-By: Maira Wenzel <[email protected]>

* Update xml/System.Windows.Forms/TextFormatFlags.xml

Co-Authored-By: Maira Wenzel <[email protected]>

* Update xml/System.Windows.Forms/TextFormatFlags.xml

Co-Authored-By: Maira Wenzel <[email protected]>

* Update xml/System.Windows.Forms/TextFormatFlags.xml

Co-Authored-By: Maira Wenzel <[email protected]>

* add missing space

Co-authored-by: Maira Wenzel <[email protected]>

Author: Tanya-Solyanik

xml/System.Windows.Forms/TextFormatFlags.xml

@@ -99,7 +99,7 @@
       </ReturnValue>
       <MemberValue>32768</MemberValue>
       <Docs>
-        <summary>Removes the end of trimmed lines, and replaces them with an ellipsis.</summary>
+        <summary>Removes the end of trimmed lines, and replaces them with an ellipsis. When used to draw text by <c>TextRenderer</c>, the string is not modified unless the <see cref="F:System.Windows.Forms.TextFormatFlags.ModifyString" /> flag is specified. Compare with <see cref="F:System.Windows.Forms.TextFormatFlags.PathEllipsis" /> and <see cref="F:System.Windows.Forms.TextFormatFlags.WordEllipsis" />.</summary>
       </Docs>
     </Member>
     <Member MemberName="ExpandTabs">
@@ -183,7 +183,7 @@
       </ReturnValue>
       <MemberValue>1048576</MemberValue>
       <Docs>
-        <summary>A legacy value that has no effect. It ignored the ampersand (&amp;) prefix character in the text, so that the letter that followed was not underlined, but other mnemonic-prefix characters were still processed.</summary>
+        <summary>Ignores the ampersand (&amp;) prefix character in the text, so that the letter that follows won't be underlined, but other mnemonic-prefix characters are still processed.</summary>
       </Docs>
     </Member>
     <Member MemberName="HorizontalCenter">
@@ -288,7 +288,7 @@
       </ReturnValue>
       <MemberValue>65536</MemberValue>
       <Docs>
-        <summary>Has no effect on the drawn text.</summary>
+        <summary>Has no effect on the drawn text or text measurements. When used to draw text by <c>TextRenderer</c>, modifies the specified string parameter to match the displayed text if ellipsis are shown. This value has no effect unless <see cref="F:System.Windows.Forms.TextFormatFlags.EndEllipsis" /> or <see cref="F:System.Windows.Forms.TextFormatFlags.PathEllipsis" /> is specified.</summary>
       </Docs>
     </Member>
     <Member MemberName="NoClipping">
@@ -393,7 +393,7 @@
       </ReturnValue>
       <MemberValue>16384</MemberValue>
       <Docs>
-        <summary>Removes the center of trimmed lines and replaces it with an ellipsis.</summary>
+        <summary>Removes the center of trimmed lines and replaces it with an ellipsis. When used to draw text by <c>TextRenderer</c>, the string is not modified unless the <see cref="F:System.Windows.Forms.TextFormatFlags.ModifyString" /> flag is specified. Compare with <see cref="F:System.Windows.Forms.TextFormatFlags.EndEllipsis" /> and <see cref="F:System.Windows.Forms.TextFormatFlags.WordEllipsis" />.</summary>
       </Docs>
     </Member>
     <Member MemberName="PrefixOnly">
@@ -414,7 +414,7 @@
       </ReturnValue>
       <MemberValue>2097152</MemberValue>
       <Docs>
-        <summary>A legacy value that has no effect. It drew only an underline at the position of the character following the ampersand (&amp;) prefix character, and did not draw any other characters in the string.</summary>
+        <summary>Draws only an underline at the position of the character following the ampersand (&amp;) prefix character and doesn't draw any other characters in the string.</summary>
       </Docs>
     </Member>
     <Member MemberName="PreserveGraphicsClipping">
@@ -624,7 +624,7 @@
       </ReturnValue>
       <MemberValue>262144</MemberValue>
       <Docs>
-        <summary>Trims the line to the nearest word and an ellipsis is placed at the end of a trimmed line.</summary>
+        <summary>Trims the line to the nearest word and an ellipsis is placed at the end of a trimmed line. Compare with <see cref="F:System.Windows.Forms.TextFormatFlags.EndEllipsis" /> and <see cref="F:System.Windows.Forms.TextFormatFlags.PathEllipsis" />.</summary>
       </Docs>
     </Member>
   </Members>