Added N&N about viewer limit

See
eclipse-platform/eclipse.platform.ui#1425
eclipse-platform/eclipse.platform.ui#818

news/4.31/platform.html

@@ -43,6 +43,51 @@ <h2>Platform and Equinox</h2>
     <h2>Views, Dialogs and Toolbar </h2>
     </td>
   </tr>
+
+  <tr id="viewer_limit_applied"> <!-- https://github.com/eclipse-platform/eclipse.platform.ui/issues/1425 -->
+      <td class="title">Viewer Limit in Workbench</td>
+      <td class="content">
+        <p>
+        Few most commonly used Eclipse views have enabled incremental view updates. 
+        These views will limit initially shown number of children to 1000 per parent element, and allow displaying next
+        batch of elements if requested. This increment number can be configured in the
+        <code>Preferences -> General -> Initial maximum number of elements shown in views</code>.
+        </p>
+        <p><img src="images/viewer_limit_preference.png" alt="New preference"/></p>
+        <p>
+        Note, that also other (3rd party) views can read the preference and enable 
+        this feature, but that must be explicitly done for each view. 
+        </p>
+        <p>
+        Incremental view updates feature was added to avoid UI freezes in large viewers, where SWT/JFace
+        hit the limits of the underlying native widget machinery while trying to render
+        thousands of elements, leading to minute lang UI freezes.
+        </p>
+        <p>
+        Incremental view update feature is currently enabled in the following views:
+        </p>
+        <ol>
+			<li>Package Explorer</li>
+			<li>Project Explorer</li>
+			<li>Problems View</li>
+			<li>Java Outline View</li>
+			<li>JUnit View</li>
+	    </ol>
+	    <p><img src="images/limit_in_package_explorer.png" alt="Package Explorer"/></p>
+	    <p><img src="images/limit_in_project_explorer.png" alt="Project Explorer"/></p>
+	    <p><img src="images/limit_in_problems_view.png" alt="Problems View"/></p>
+	    <p><img src="images/limit_in_outline_view.png" alt="Java Outline"/></p>
+	    <p><img src="images/limit_in_junit_view.png" alt="JUnit View"/></p>
+	    <p>
+		This new preference can be disabled in products by specifying
+		<code>org.eclipse.ui.workbench/largeViewLimit=0</code> in the
+		<code>plugin_customization.ini</code> file or via Oomph. 
+		In the same way the preference can be changed for products that need a lower
+		or higher limit. 	
+        </p>
+      </td>
+  </tr>
+
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news/4.31/platform_isv.html

@@ -38,6 +38,42 @@ <h2>Platform and Equinox API</h2>
   <tr>
     <td id="Platform" class="section" colspan="2"><h2>Platform Changes</h2></td>
   </tr>
+
+  <tr id="viewer_limit_jface"> <!-- https://github.com/eclipse-platform/eclipse.platform.ui/issues/1425 -->
+      <td class="title">Viewer Limit in JFace</td>
+      <td class="content">
+        <p>
+        <code>org.eclipse.jface.viewers.ColumnViewer.setDisplayIncrementally(int incrementSize)</code> API was added to
+        JFace. If <code>incrementSize</code> is set to some positive value, viewer will show 
+        initially not more as this number of child elements per parent.
+        Additionally, viewer will also provide a way to user to show more elements if available/needed.
+        This API solves the problem with UI hangs in case viewer tries to display a large number of child elements per parent.
+        </p>
+        <p>
+        This feature is currently implemented in <code>org.eclipse.jface.viewers.TableViewer</code> 
+        and <code>org.eclipse.jface.viewers.TreeViewer</code> but not enabled by default 
+        (<code>incrementSize</code> is zero by default).
+        Each concrete viewer implementation is responsible to enable this feature if needed.
+        </p>
+        <p>Note, that even if it was designed to be backwards compatible API (as much as possible),
+        there could be some regressions while converting existing viewers code to use
+        the new API. Please consider to test carefully your code if enabling this functionality!
+        </p>
+      </td>
+  </tr>
+
+  <tr id="viewer_limit_workbench"> <!-- https://github.com/eclipse-platform/eclipse.platform.ui/issues/1425 -->
+      <td class="title">Viewer Limit in Workbench</td>
+      <td class="content">
+        <p>Complementary to the JFace API above, <code>org.eclipse.ui.IWorkbenchPreferenceConstants</code> and
+        <code>org.eclipse.ui.views.WorkbenchViewerSetup</code> API's were added.
+        This API provides default workbench preference access and convenient way for Viewers
+        that want apply default workbench value and don't want to write extra code to
+        keep watching for preference change.
+        </p>
+      </td>
+  </tr>
+
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