Update documentation to cover editing difficulty names

Also update the screenshot of the Difficulty Editor to reflect the latest
layout changes (including the switch from wxNotebook to wxChoicebook).

doc/manual.adoc

@@ -1503,11 +1503,12 @@ removing a particular enemy type's ability to relight torches.
 .The Difficulty editor, showing a modified property on a particular entity class
 image::DifficultyEditor.png[align="center"]
 
-The Difficulty editor consists of a tabbed widget, where each tab contains the
-settings which correspond to a particular difficulty level. The difficulty names
-are shown for the current map — normally these will be the default values of
-"Easy", "Medium" and "Difficult", but if the current map has customised
-difficulty names DarkRadiant will adjust the tab names accordingly.
+The Difficulty editor shows the names of the available difficulty levels in a
+dropdown widget, beneath which are the settings for the selected difficulty
+level. The difficulty names are customisable on a per-map basis — normally these
+will be the default values of "Easy", "Medium" and "Difficult", but if the
+current map has customised difficulty names DarkRadiant will adjust the tab
+names accordingly.
 
 On the left is a tree view showing all of the property overrides for the current
 difficulty level. Each top-level item is a particular entity class, which
@@ -1529,9 +1530,14 @@ all enemies of this particular type will not be able to relight torches.
  assignments from the list; to remove all of the assignments for a particular
  entity class, you must select and delete each one individually.
 
+*Editing the difficulty name*:: To edit the name of the current difficulty
+ level, click the edit button to the right of the dropdown, and enter a new name
+ in the text box. The modified name will be written into a property on the
+ `worldspawn` entity and reflected both in game and in DarkRadiant.
+
 TIP: For details of more advanced difficulty-dependent changes, such as
 modifying the behaviour of a *single* entity (rather than an entire entity
-class), or changing the names of difficulty settings, consult the Dark Mod Wiki.
+class), consult the Dark Mod Wiki.
 
 == Command reference
 

doc/manual.html

@@ -3016,11 +3016,12 @@ <h3 id="_the_difficulty_editor">The Difficulty editor</h3>
 <div class="title">Figure 12. The Difficulty editor, showing a modified property on a particular entity class</div>
 </div>
 <div class="paragraph">
-<p>The Difficulty editor consists of a tabbed widget, where each tab contains the
-settings which correspond to a particular difficulty level. The difficulty names
-are shown for the current map — normally these will be the default values of
-"Easy", "Medium" and "Difficult", but if the current map has customised
-difficulty names DarkRadiant will adjust the tab names accordingly.</p>
+<p>The Difficulty editor shows the names of the available difficulty levels in a
+dropdown widget, beneath which are the settings for the selected difficulty
+level. The difficulty names are customisable on a per-map basis — normally these
+will be the default values of "Easy", "Medium" and "Difficult", but if the
+current map has customised difficulty names DarkRadiant will adjust the tab
+names accordingly.</p>
 </div>
 <div class="paragraph">
 <p>On the left is a tree view showing all of the property overrides for the current
@@ -3049,6 +3050,13 @@ <h3 id="_the_difficulty_editor">The Difficulty editor</h3>
 assignments from the list; to remove all of the assignments for a particular
 entity class, you must select and delete each one individually.</p>
 </dd>
+<dt class="hdlist1"><strong>Editing the difficulty name</strong></dt>
+<dd>
+<p>To edit the name of the current difficulty
+level, click the edit button to the right of the dropdown, and enter a new name
+in the text box. The modified name will be written into a property on the
+<code>worldspawn</code> entity and reflected both in game and in DarkRadiant.</p>
+</dd>
 </dl>
 </div>
 <div class="admonitionblock tip">
@@ -3060,7 +3068,7 @@ <h3 id="_the_difficulty_editor">The Difficulty editor</h3>
 <td class="content">
 For details of more advanced difficulty-dependent changes, such as
 modifying the behaviour of a <strong>single</strong> entity (rather than an entire entity
-class), or changing the names of difficulty settings, consult the Dark Mod Wiki.
+class), consult the Dark Mod Wiki.
 </td>
 </tr>
 </table>
@@ -3723,7 +3731,7 @@ <h4 id="_creating_an_assets_lst_file">Creating an assets.lst file</h4>
 </div>
 <div id="footer">
 <div id="footer-text">
-Last updated 2020-03-10 21:18:41 GMT
+Last updated 2020-04-07 20:18:29 BST
 </div>
 </div>
 </body>