title: MacOS 10.12, WKWebView problem with file input
body: <p>I develop an application with WKWebView for web application. Native app is just container for web application.</p>
  <p>XCode: 11.3.1,
  Deployment target: MacOS 10.12</p>
  <p>10.13 - 10.15 - work's as expected, but 10.12 can't upload files throw input type=&quot;file&quot;</p>
  <p>runOpenPanelWith implementation</p>
  <pre><code>func webView(_ webView: WKWebView, runOpenPanelWith parameters: WKOpenPanelParameters, initiatedByFrame frame: WKFrameInfo, completionHandler: @escaping ([URL]?) -&gt; Void) {
          let openPanel = NSOpenPanel()
          openPanel.canChooseFiles = true
          openPanel.begin { (result) in
              NSLog(&quot;Selected result &quot; + result.rawValue.description)
              if result == NSApplication.ModalResponse.OK {
                  if let url = openPanel.url {
                      completionHandler([url])
                  }
              } else if result == NSApplication.ModalResponse.cancel {
                  completionHandler(nil)
              }
          }
      }
  </code></pre>
  <p>Debug from js:</p>
  <pre><code>window.addEventListener('paste', (event) =&gt; {
      console.log(event.clipboardData.items);
  )
  // null
  
  fileInput.addEventListener('change', () =&gt; {
      console.log(fileInput.files[0].size);
  })
  // 0
  </code></pre>
  <p>Doesn't work throw copy-paste and doesn't work throw open panel.</p>
  <p>What broken in 10.12 or maybe I need something specific for 10.12?</p>