Add editor/viewer toggle feature

novelwriter/gui/docviewer.py

@@ -282,6 +282,10 @@ class GuiDocViewer(QTextBrowser):
             return False
         return True
 
+    def anyFocus(self) -> bool:
+        """Check if any widget or child widget has focus."""
+        return self.hasFocus() or self.isAncestorOf(QApplication.focusWidget())
+
     def clearNavHistory(self) -> None:
         """Clear the navigation history."""
         self.docHistory.clear()