Do not intercept characters typed into input boxes

In order to allow some user interaction on the article view, we need
WkWebView to behave like legacy WebView on <input> and <textarea>
elements.

Issue #1793

Vienna/Sources/Main window/WebKitArticleView.swift

@@ -67,7 +67,19 @@ class WebKitArticleView: CustomWKWebView, ArticleContentView, WKNavigationDelega
 
     /// handle special keys when the article view has the focus
     override func keyDown(with event: NSEvent) {
-        if let pressedKeys = event.characters, pressedKeys.count == 1 {
+        var interceptKey = true
+        waitForAsyncExecution(until: DispatchTime.now() + DispatchTimeInterval.milliseconds(200)) { finishHandler in
+            self.evaluateJavaScript("document.activeElement.tagName") { res, _ in
+                guard let res = res as? String else {
+                    return
+                }
+                if ["INPUT", "TEXTAREA"].contains(res) {
+                    interceptKey = false
+                }
+                finishHandler()
+            }
+        }
+        if interceptKey, let pressedKeys = event.characters, pressedKeys.count == 1 {
             let pressedKey = (pressedKeys as NSString).character(at: 0)
             // give app controller preference when handling commands
             if NSApp.appController.handleKeyDown(pressedKey, withFlags: event.modifierFlags.rawValue) {