<h2 dir="auto">Steps to Reproduce</h2>
<h1 dir="auto">issue1</h1>
<p dir="auto">when background is an opacity color，a line will show at top.</p>
<div class="highlight highlight-source-dart notranslate position-relative overflow-auto" dir="auto" data-snippet-clipboard-copy-content="var color = Color(0xfffe7801);
 var colorb = color.withOpacity(0.1);

    Paint paint=new Paint();
    paint.color = colorb;
   var ts = Text(
        &quot;  悬赏 ￥ &quot; +&quot;ddddddddddddd&quot; + &quot;  &quot;,
        style: TextStyle(color: color, background: paint, fontSize: 13.0,));"><pre class="notranslate"><span class="pl-k">var</span> color <span class="pl-k">=</span> <span class="pl-c1">Color</span>(<span class="pl-c1">0xfffe7801</span>);
 <span class="pl-k">var</span> colorb <span class="pl-k">=</span> color.<span class="pl-en">withOpacity</span>(<span class="pl-c1">0.1</span>);

    <span class="pl-c1">Paint</span> paint<span class="pl-k">=</span><span class="pl-k">new</span> <span class="pl-c1">Paint</span>();
    paint.color <span class="pl-k">=</span> colorb;
   <span class="pl-k">var</span> ts <span class="pl-k">=</span> <span class="pl-c1">Text</span>(
        <span class="pl-s">"  悬赏 ￥ "</span> <span class="pl-k">+</span><span class="pl-s">"ddddddddddddd"</span> <span class="pl-k">+</span> <span class="pl-s">"  "</span>,
        style<span class="pl-k">:</span> <span class="pl-c1">TextStyle</span>(color<span class="pl-k">:</span> color, background<span class="pl-k">:</span> paint, fontSize<span class="pl-k">:</span> <span class="pl-c1">13.0</span>,));</pre></div>
<h1 dir="auto">issue2</h1>
<p dir="auto">when background is an opacity 1.0 color, the Chinese words is missing.</p>
<div class="highlight highlight-source-dart notranslate position-relative overflow-auto" dir="auto" data-snippet-clipboard-copy-content="var color=Colors.black;
    var colorb=Colors.green;
    Paint paint=new Paint();
    paint.color = colorb;
   var ts = Text(
        &quot;  悬赏 ￥ &quot; +&quot;ddddddddddddd&quot; + &quot;  &quot;,
        style: TextStyle(color: color, background: paint, fontSize: 13.0,));"><pre class="notranslate"><span class="pl-k">var</span> color<span class="pl-k">=</span><span class="pl-c1">Colors</span>.black;
    <span class="pl-k">var</span> colorb<span class="pl-k">=</span><span class="pl-c1">Colors</span>.green;
    <span class="pl-c1">Paint</span> paint<span class="pl-k">=</span><span class="pl-k">new</span> <span class="pl-c1">Paint</span>();
    paint.color <span class="pl-k">=</span> colorb;
   <span class="pl-k">var</span> ts <span class="pl-k">=</span> <span class="pl-c1">Text</span>(
        <span class="pl-s">"  悬赏 ￥ "</span> <span class="pl-k">+</span><span class="pl-s">"ddddddddddddd"</span> <span class="pl-k">+</span> <span class="pl-s">"  "</span>,
        style<span class="pl-k">:</span> <span class="pl-c1">TextStyle</span>(color<span class="pl-k">:</span> color, background<span class="pl-k">:</span> paint, fontSize<span class="pl-k">:</span> <span class="pl-c1">13.0</span>,));</pre></div>
<p dir="auto">I want to add a background to text, here is my code:</p>
<div class="highlight highlight-source-dart notranslate position-relative overflow-auto" dir="auto" data-snippet-clipboard-copy-content="RichText(
                text: TextSpan(
                        text: &quot;不科学1111&quot;,
                        style: TextStyle(
                          color: Colors.black,
                          background: new Paint()..color = Colors.pinkAccent,
                        ),
                    children: [
                          TextSpan(
                            text: &quot;不科学sdfsdfkd&quot;,
                            style: TextStyle(
                              color: Colors.lightGreenAccent,
                              background: new Paint()
                                ..color = Colors.pinkAccent,
                            ),
                          ),
                        ]),
                  ),"><pre class="notranslate"><span class="pl-c1">RichText</span>(
                text<span class="pl-k">:</span> <span class="pl-c1">TextSpan</span>(
                        text<span class="pl-k">:</span> <span class="pl-s">"不科学1111"</span>,
                        style<span class="pl-k">:</span> <span class="pl-c1">TextStyle</span>(
                          color<span class="pl-k">:</span> <span class="pl-c1">Colors</span>.black,
                          background<span class="pl-k">:</span> <span class="pl-k">new</span> <span class="pl-c1">Paint</span>()..color <span class="pl-k">=</span> <span class="pl-c1">Colors</span>.pinkAccent,
                        ),
                    children<span class="pl-k">:</span> [
                          <span class="pl-c1">TextSpan</span>(
                            text<span class="pl-k">:</span> <span class="pl-s">"不科学sdfsdfkd"</span>,
                            style<span class="pl-k">:</span> <span class="pl-c1">TextStyle</span>(
                              color<span class="pl-k">:</span> <span class="pl-c1">Colors</span>.lightGreenAccent,
                              background<span class="pl-k">:</span> <span class="pl-k">new</span> <span class="pl-c1">Paint</span>()
                                ..color <span class="pl-k">=</span> <span class="pl-c1">Colors</span>.pinkAccent,
                            ),
                          ),
                        ]),
                  ),</pre></div>
<p dir="auto">But the Simplified Chinese words do not display:<br>
<a target="_blank" rel="noopener noreferrer nofollow" href="https://user-images.githubusercontent.com/17703630/48473171-eacb4900-e832-11e8-9395-ac66c99cb3e9.png"><img src="https://user-images.githubusercontent.com/17703630/48473171-eacb4900-e832-11e8-9395-ac66c99cb3e9.png" alt="image" style="max-width: 100%;"></a></p>
<p dir="auto">If I set the background color with opacity, it seems well:</p>
<div class="highlight highlight-source-dart notranslate position-relative overflow-auto" dir="auto" data-snippet-clipboard-copy-content="RichText(
                text: TextSpan(
                      text: &quot;不科学1111&quot;,
                      style: TextStyle(
                        color: Colors.black,
                        background: new Paint()..color = Colors.pinkAccent.withOpacity(0.5),
                      ),
                    children: [
                        TextSpan(
                          text: &quot;不科学sdfsdfkd&quot;,
                          style: TextStyle(
                            color: Colors.lightGreenAccent,
                            background: new Paint()
                              ..color = Colors.pinkAccent,
                            ),
                          ),
                        ]),
                  )"><pre class="notranslate"><span class="pl-c1">RichText</span>(
                text<span class="pl-k">:</span> <span class="pl-c1">TextSpan</span>(
                      text<span class="pl-k">:</span> <span class="pl-s">"不科学1111"</span>,
                      style<span class="pl-k">:</span> <span class="pl-c1">TextStyle</span>(
                        color<span class="pl-k">:</span> <span class="pl-c1">Colors</span>.black,
                        background<span class="pl-k">:</span> <span class="pl-k">new</span> <span class="pl-c1">Paint</span>()..color <span class="pl-k">=</span> <span class="pl-c1">Colors</span>.pinkAccent.<span class="pl-en">withOpacity</span>(<span class="pl-c1">0.5</span>),
                      ),
                    children<span class="pl-k">:</span> [
                        <span class="pl-c1">TextSpan</span>(
                          text<span class="pl-k">:</span> <span class="pl-s">"不科学sdfsdfkd"</span>,
                          style<span class="pl-k">:</span> <span class="pl-c1">TextStyle</span>(
                            color<span class="pl-k">:</span> <span class="pl-c1">Colors</span>.lightGreenAccent,
                            background<span class="pl-k">:</span> <span class="pl-k">new</span> <span class="pl-c1">Paint</span>()
                              ..color <span class="pl-k">=</span> <span class="pl-c1">Colors</span>.pinkAccent,
                            ),
                          ),
                        ]),
                  )</pre></div>
<p dir="auto"><a target="_blank" rel="noopener noreferrer nofollow" href="https://user-images.githubusercontent.com/17703630/48473353-3a117980-e833-11e8-859b-c8700ce5474c.png"><img src="https://user-images.githubusercontent.com/17703630/48473353-3a117980-e833-11e8-859b-c8700ce5474c.png" alt="image" style="max-width: 100%;"></a><br>
But it still doesn't meet my expectation:<br>
<a target="_blank" rel="noopener noreferrer nofollow" href="https://user-images.githubusercontent.com/17703630/48473394-56adb180-e833-11e8-8b71-203ba7d7416c.png"><img src="https://user-images.githubusercontent.com/17703630/48473394-56adb180-e833-11e8-8b71-203ba7d7416c.png" alt="image" style="max-width: 100%;"></a></p>
<p dir="auto">I have added app locales supports like this:</p>
<div class="highlight highlight-source-dart notranslate position-relative overflow-auto" dir="auto" data-snippet-clipboard-copy-content="supportedLocales: [
            const Locale('zh', 'CH'),
            const Locale('en', 'US'),
          ],
"><pre class="notranslate">supportedLocales<span class="pl-k">:</span> [
            <span class="pl-k">const</span> <span class="pl-c1">Locale</span>(<span class="pl-s">'zh'</span>, <span class="pl-s">'CH'</span>),
            <span class="pl-k">const</span> <span class="pl-c1">Locale</span>(<span class="pl-s">'en'</span>, <span class="pl-s">'US'</span>),
          ],
</pre></div>
<p dir="auto">Still doesn't work.</p>