<h2 dir="auto">Steps to Reproduce</h2>
<p dir="auto">I see Row and Column widgets as a <a href="https://developer.apple.com/documentation/uikit/uistackview" rel="nofollow">UIStackView</a> and would expect spacing parameter so that we can add custom spacing between their children. Something like <a href="https://developer.apple.com/documentation/uikit/uistackview/1616225-spacing" rel="nofollow">spacing</a>.<br>
I always end up adding additional Containers in between and this is far from clean solution from my pov - something like this:</p>
<div class="highlight highlight-source-dart notranslate position-relative overflow-auto" dir="auto" data-snippet-clipboard-copy-content="new Column(
  crossAxisAlignment: CrossAxisAlignment.start,
  children: &lt;Widget&gt;[
    new Container(
      height: 20.0,
      child: new Image.asset('assets/images/someimage.png'),
    ),
    new Container(
      height: 8.0,
    ),
    new Container(
      height: 20.0,
      child: new Image.asset('assets/images/someimage.png'),
    ),
  )
)"><pre class="notranslate"><span class="pl-k">new</span> <span class="pl-c1">Column</span>(
  crossAxisAlignment<span class="pl-k">:</span> <span class="pl-c1">CrossAxisAlignment</span>.start,
  children<span class="pl-k">:</span> <span class="pl-k">&lt;</span><span class="pl-c1">Widget</span><span class="pl-k">&gt;</span>[
    <span class="pl-k">new</span> <span class="pl-c1">Container</span>(
      height<span class="pl-k">:</span> <span class="pl-c1">20.0</span>,
      child<span class="pl-k">:</span> <span class="pl-k">new</span> <span class="pl-c1">Image</span>.<span class="pl-en">asset</span>(<span class="pl-s">'assets/images/someimage.png'</span>),
    ),
    <span class="pl-k">new</span> <span class="pl-c1">Container</span>(
      height<span class="pl-k">:</span> <span class="pl-c1">8.0</span>,
    ),
    <span class="pl-k">new</span> <span class="pl-c1">Container</span>(
      height<span class="pl-k">:</span> <span class="pl-c1">20.0</span>,
      child<span class="pl-k">:</span> <span class="pl-k">new</span> <span class="pl-c1">Image</span>.<span class="pl-en">asset</span>(<span class="pl-s">'assets/images/someimage.png'</span>),
    ),
  )
)</pre></div>
<p dir="auto">I understand that there are other ways to do this but all of them induce extra logic and make code harder to read.</p>
<p dir="auto">In cases when a variable is initialized using a literal (<code class="notranslate">String</code>, <code class="notranslate">int</code>, <code class="notranslate">bool</code>, <code class="notranslate">double</code>, <code class="notranslate">List</code>, <code class="notranslate">Map</code>) or a constructor initialization type annotations do not contribute to type safety, but have net negative effect on code readability:</p>
<div class="highlight highlight-source-dart notranslate position-relative overflow-auto" dir="auto" data-snippet-clipboard-copy-content="String greeting = 'Hello, World!';
double d = 4.5;
MyAwesomeWidget widget = new MyAwesomeWidget();
final Map&lt;String, List&lt;int&gt;&gt; measurements = &lt;String, List&lt;int&gt;&gt;{};"><pre class="notranslate"><span class="pl-c1">String</span> greeting <span class="pl-k">=</span> <span class="pl-s">'Hello, World!'</span>;
<span class="pl-c1">double</span> d <span class="pl-k">=</span> <span class="pl-c1">4.5</span>;
<span class="pl-c1">MyAwesomeWidget</span> widget <span class="pl-k">=</span> <span class="pl-k">new</span> <span class="pl-c1">MyAwesomeWidget</span>();
<span class="pl-k">final</span> <span class="pl-c1">Map</span>&lt;<span class="pl-c1">String</span>, <span class="pl-c1">List</span>&lt;<span class="pl-c1">int</span>&gt;&gt; measurements <span class="pl-k">=</span> <span class="pl-k">&lt;</span><span class="pl-c1">String</span>, <span class="pl-c1">List</span>&lt;<span class="pl-c1">int</span>&gt;<span class="pl-k">&gt;</span>{};</pre></div>
<p dir="auto">The following has as much type safety but better readability:</p>
<div class="highlight highlight-source-dart notranslate position-relative overflow-auto" dir="auto" data-snippet-clipboard-copy-content="var greeting = 'Hello, World!';
var d = 4.5;
var widget = new MyAwesomeWidget();
final measurements = &lt;String, List&lt;int&gt;&gt;{};"><pre class="notranslate"><span class="pl-k">var</span> greeting <span class="pl-k">=</span> <span class="pl-s">'Hello, World!'</span>;
<span class="pl-k">var</span> d <span class="pl-k">=</span> <span class="pl-c1">4.5</span>;
<span class="pl-k">var</span> widget <span class="pl-k">=</span> <span class="pl-k">new</span> <span class="pl-c1">MyAwesomeWidget</span>();
<span class="pl-k">final</span> measurements <span class="pl-k">=</span> <span class="pl-k">&lt;</span><span class="pl-c1">String</span>, <span class="pl-c1">List</span>&lt;<span class="pl-c1">int</span>&gt;<span class="pl-k">&gt;</span>{};</pre></div>
<p dir="auto">Type annotations still contribute to type safety when the initializing expression is missing (i.e. <code class="notranslate">null</code>) or is non-trivial:</p>
<div class="highlight highlight-source-dart notranslate position-relative overflow-auto" dir="auto" data-snippet-clipboard-copy-content="String greeting;
String greeting = null;
String greeting = condition ? hello : goodbye;
String greeting = fetchGreeting();"><pre class="notranslate"><span class="pl-c1">String</span> greeting;
<span class="pl-c1">String</span> greeting <span class="pl-k">=</span> <span class="pl-c1">null</span>;
<span class="pl-c1">String</span> greeting <span class="pl-k">=</span> condition <span class="pl-k">?</span> hello <span class="pl-k">:</span> goodbye;
<span class="pl-c1">String</span> greeting <span class="pl-k">=</span> <span class="pl-en">fetchGreeting</span>();</pre></div>