title: Inkwell does not appear in custom button
body: <p>When the <code>sized box</code> tapped, the <code>ripple effect</code> should happen on top of the widget. But it does not appear. The sized box appears, but ripple effect is not.</p>
  <pre><code>      Stack(
          alignment: Alignment.center,
          children: &lt;Widget&gt;[
            SizedBox(
              width: widget.width,
              height: widget.height,
              child: Material(color: Colors.yellow, child: widget.icon
                 
                  ),
  
            ),
            SizedBox(
              width: widget.width,
              height: widget.height,
              child: InkWell(
                  borderRadius: BorderRadius.circular(25),
                  splashColor: Colors.purple,
                  onTap: () {}),
            ),
          ],
        ),
      ]);
  </code></pre>
  <p><strong>EDIT:</strong> <code>Wrapped</code> the whole <code>stack</code> with the <code>inkwell</code> but still ripple does not appear.</p>
  <pre><code>InkWell(
          borderRadius: BorderRadius.circular(25),
          splashColor: Colors.purple,
          child: Stack(
            alignment: Alignment.center,
            children: &lt;Widget&gt;[
              SizedBox(
                width: widget.width,
                height: widget.height,
                child: Material(color: Colors.yellow, child: widget.icon
                    
                    ),
  </code></pre>