New Demo Program - Multiline Element clipboard operations using a right click menu

DemoPrograms/Demo_Multiline_Right_Click_Menu_Clipboard.py

@@ -0,0 +1,62 @@
+import PySimpleGUI as sg
+
+"""
+    Demo - Adding a right click menu to perform multiline element common operations
+
+    Sometimes Multiline Elements can benefit from a right click menu. There are no default menu
+    that come with tkinter, so you'll need to create your own.
+
+    Some common clipboard types of operations
+        Select all
+        Copy
+        Paste
+        Cut
+
+    The underlying Widget is accessed several times in this code because setting selections,
+    getting their values, and clipboard operations are not currently exposed in the APIs
+
+    NOTE - With tkinter, if you use the built-in clipboard, you must keep your program
+    running in order to access the clipboard.  Upon exit, your clipboard will be deleted.
+    You can get around this by using other clipboard packages.
+
+    Copyright 2021 PySimpleGUI
+"""
+
+right_click_menu = ['', ['Copy', 'Paste', 'Select All', 'Cut']]
+MLINE_KEY = '-MLINE-'
+
+layout = [  [sg.Text('Using a custom right click menu with Multiline Element')],
+            [sg.Multiline(size=(60,20), key=MLINE_KEY, right_click_menu=right_click_menu)],
+            [sg.B('Go'), sg.B('Exit')]]
+
+window = sg.Window('Right Click Menu Multiline', layout)
+
+mline:sg.Multiline = window[MLINE_KEY]
+
+while True:
+    event, values = window.read()       # type: (str, dict)
+    print(event, values)
+    if event in (sg.WIN_CLOSED, 'Exit'):
+        break
+    if event == 'Select All':
+        mline.Widget.selection_clear()
+        mline.Widget.tag_add('sel', '1.0', 'end')
+    elif event == 'Copy':
+        try:
+            text = mline.Widget.selection_get()
+            window.TKroot.clipboard_clear()
+            window.TKroot.clipboard_append(text)
+        except:
+            print('Nothing selected')
+    elif event == 'Paste':
+        mline.Widget.insert(sg.tk.INSERT, window.TKroot.clipboard_get())
+    elif event == 'Cut':
+        try:
+            text = mline.Widget.selection_get()
+            window.TKroot.clipboard_clear()
+            window.TKroot.clipboard_append(text)
+            mline.update('')
+        except:
+            print('Nothing selected')
+
+window.close()