【fix】快捷键关闭标签，兼容在有窗口弹起的场景

PDF Office/PDF Master/AppDelegate.swift

@@ -344,6 +344,10 @@ class AppDelegate: NSObject, NSApplicationDelegate, iRateDelegate{
             if browser.tabCount() == 1 {
                 windowControler?.window?.close()
             } else {
+                if let _ = windowControler?.window?.attachedSheet {
+                    NSSound.beep()
+                    return
+                }
                 browser.closeTab()
             }
         } else {