Quickly add GUI to script Recipe

docs/cookbook.md

@@ -66,6 +66,28 @@ Browse for a filename that is populated into the input field.
     print(button, source_filename)
 
 --------------------------
+## Add GUI to Front-End of Script
+Quickly add a GUI allowing the user to browse for a filename if a filename is not supplied on the command line using this 1-line GUI. It's the best of both worlds.
+
+    import PySimpleGUI as sg
+    import sys
+
+    if len(sys.argv) == 1:
+        button, (fname,) = sg.FlexForm('My Script').LayoutAndRead([[sg.T('Document to open')],
+                                                               [sg.In(), sg.FileBrowse()],
+                                                               [sg.Open(), sg.Cancel()]])
+    else:
+        fname = sys.argv[1]
+
+    if not fname:
+        sg.MsgBox("Cancel", "No filename supplied")
+        raise SystemExit("Cancelling: no filename supplied")
+
+
+![script front-end](https://user-images.githubusercontent.com/13696193/44756573-39e9c380-aaf9-11e8-97b4-6679f9f5bd46.jpg)
+
+--------------
+
 ## Compare 2 Files
 
 Browse to get 2 file names that can be then compared.  Uses a context manager