[release-notes/gnome-3-20] developers - add notes on gtk+. these need writing up

[Allan Day <allanday src gnome org>]

commit 7751e4805aef138ef0a82064e0ad79f896f41cb4
Author: Allan Day <allanpday gmail com>
Date:   Sun Mar 13 14:05:25 2016 +0000

    developers - add notes on gtk+. these need writing up

 help/C/developers.page |   51 ++++++++++++++++++++++++++++++++++++++++++++++++
 1 files changed, 51 insertions(+), 0 deletions(-)
---
diff --git a/help/C/developers.page b/help/C/developers.page
index 2666055..39a7fb1 100644
--- a/help/C/developers.page
+++ b/help/C/developers.page
@@ -116,6 +116,57 @@ give it a try and see how you like it!</p>
   <section id="gtk+">
     <title>GTK+</title>
     <media type="image" src="figures/placeholder.png"/>
+    <p>It has been a big cycle for GTK+, with major changes to CSS styling:</p>
+    <list>
+      <item><p>GTK+ now supports the CSS box model much more consistently, so
+      theme authors can use margins, padding, min-width, min-height like you
+      would on the web.</p></item>
+      <item><p>Widget documentation now describes CSS element names and style
+      classes have been documented (see the CSS nodes section of the
+      documentation for each widget, and <link
+      href="https://developer.gnome.org/gtk3/unstable/theming.html";>theming in
+      GTK+ overview</link>.</p></item>
+      <item><p>New CSS features are now supported, including <code>
+      radial-gradient()</code>, <code>rem</code> and <code>calc()</code>.</p>
+      </item>
+      <item><p>As a part of GTK+'s transition to CSS theming, many style
+      properties have been deprecated in favor of CSS equivalents.</p></item>
+    </list>
+    <p>These changes mean that existing custom CSS and themes will need to be
+    updated for GTK+ 3.20, but the CSS interface will be stable in the future.
+    </p>
+    <p><code>GtkShortcutsWindow</code> - a new widget to present a handy
+    overview of keyboard shortcuts and multitouch gestures in your application.
+    Describe features here.</p>
+    <p>Other changes in GTK+ 3.20:</p>
+    <list>
+      <item><p><code>gtk-query-settings</code> is a new commandline utility to
+      query GTK+ settings that your application would see.</p></item>
+      <item><p><code>gtk-builder-tool</code> has a new preview command to test
+      .ui files.</p></item>
+<!-- TODO: what kind of issues does gtk-builder-tool allow you to test for? Why is it useful? -->
+      <item><p><code>gtk3-demo</code> now has a <gui>foreign drawing</gui> demo
+      that shows how to style non-GTK+ widgets with a GTK+ CSS visual theme.</p>
+      </item>
+      <item><p><code>GtkWindow</code> sizing behavior has been improved to work
+      with client-side decorations. This means that <code>
+      gtk_window_set_default_size()</code> must now be combined with
+      <code>gtk_window_get_size()</code>: see the <link
+      href="https://wiki.gnome.org/HowDoI/SaveWindowState";>save window state
+      </link> for information on best-practices for saving window size.</p>
+      </item>
+    </list>
+  </section>
+
+  <section id="gtk-inspector">
+    <title>GTK+ Inspector</title>
+    <list>
+      <item><p>Some UI improvements (dropped sidebar, cleaned up some lists and
+      trees visually).</p></item>
+      <item><p>Shows input device information (in the general tab).</p></item>
+      <item><p>Shows CSS nodes and associated style information.</p></item>
+      <item><p>Can highlight widgets that are causing resizes.</p></item>
+    </list>
   </section>
 
   <section id="glib">