<p dir="auto">Currently to get the size of a widget you need to do this:</p>
<div class="highlight highlight-source-dart notranslate position-relative overflow-auto" dir="auto" data-snippet-clipboard-copy-content="  Size get _size {
    assert(mounted);
    RenderBox box = context.findRenderObject();
    assert(box != null);
    assert(box.hasSize);
    return box.size;
  }"><pre class="notranslate">  <span class="pl-c1">Size</span> <span class="pl-k">get</span> _size {
    <span class="pl-k">assert</span>(mounted);
    <span class="pl-c1">RenderBox</span> box <span class="pl-k">=</span> context.<span class="pl-en">findRenderObject</span>();
    <span class="pl-k">assert</span>(box <span class="pl-k">!=</span> <span class="pl-c1">null</span>);
    <span class="pl-k">assert</span>(box.hasSize);
    <span class="pl-k">return</span> box.size;
  }</pre></div>
<p dir="auto">It'd be nice to have this as a built in api.</p>
<p dir="auto">((I'm copying this code all over the place.))</p>
<p dir="auto">Similarly getting the size of the widget via  GlobalKey would be good too.  Maybe something can be added to GlobalKey?</p>
<p dir="auto">In the tabs section of the gallery, the beach ball can get in a state where it sits slightly under the header.  The resting state should be sitting fully underneath the header.</p>
<p dir="auto">Steps to Reproduce</p>
<ul dir="auto">
<li>Build and install latest Flutter Gallery from the repo, enter "Tabs" section,</li>
<li>scroll "Left" section to the bottom,</li>
<li>select to "Right" tab,</li>
<li>Notice that the beach ball is scrolled under the header a little bit, and will sit there.</li>
</ul>
<p dir="auto"><a target="_blank" rel="noopener noreferrer nofollow" href="https://user-images.githubusercontent.com/9346834/27092131-5d79b4c4-5030-11e7-9305-0bf7f51e7f98.png"><img width="369" alt="screen shot 2017-06-13 at 12 02 53 pm" src="https://user-images.githubusercontent.com/9346834/27092131-5d79b4c4-5030-11e7-9305-0bf7f51e7f98.png" style="max-width: 100%;"></a></p>
<p dir="auto">Flutter Doctor</p>
<p dir="auto">[✓] Flutter (on Mac OS X 10.12.4 16E195, locale en-US, channel master)<br>
• Flutter at /Users/KG/Developer/Flutter/flutter<br>
• Framework revision <a class="commit-link" data-hovercard-type="commit" data-hovercard-url="https://github.com/flutter/flutter/commit/37e32d5aeec9e4ab79c7d5987db97c4bb9cd8181/hovercard" href="https://github.com/flutter/flutter/commit/37e32d5aeec9e4ab79c7d5987db97c4bb9cd8181"><tt>37e32d5</tt></a> (21 hours ago), 2017-06-12 12:23:13 -0700<br>
• Engine revision <a class="commit-link" data-hovercard-type="commit" data-hovercard-url="https://github.com/flutter/flutter/commit/ffe8181ffe7432b61a67323c80fd8025704e4695/hovercard" href="https://github.com/flutter/flutter/commit/ffe8181ffe7432b61a67323c80fd8025704e4695"><tt>ffe8181</tt></a><br>
• Tools Dart version 1.24.0-dev.6.7</p>
<p dir="auto">[✓] Android toolchain - develop for Android devices (Android SDK 25.0.3)<br>
• Android SDK at /Users/KG/Library/Android/sdk<br>
• Platform android-25, build-tools 25.0.3<br>
• ANDROID_HOME = /Users/KG/Library/Android/sdk<br>
• Java binary at: /Applications/Android Studio.app/Contents/jre/jdk/Contents/Home/bin/java<br>
• Java version OpenJDK Runtime Environment (build 1.8.0_112-release-b06)</p>
<p dir="auto">[✓] iOS toolchain - develop for iOS devices (Xcode 8.3.3)<br>
• Xcode at /Applications/Xcode.app/Contents/Developer<br>
• Xcode 8.3.3, Build version 8E3004b<br>
• ios-deploy 1.9.1<br>
• CocoaPods version 1.2.1</p>
<p dir="auto">[✓] Android Studio (version 2.3)<br>
• Android Studio at /Applications/Android Studio.app/Contents<br>
• Gradle version 3.2<br>
• Java version OpenJDK Runtime Environment (build 1.8.0_112-release-b06)</p>
<p dir="auto">[✓] IntelliJ IDEA Community Edition (version 2017.1.4)<br>
• Flutter plugin version 14.0<br>
• Dart plugin version 171.4694.29</p>