New Demo - input validation

DemoPrograms/Demo_Input_Validation.py

@@ -0,0 +1,27 @@
+import sys
+if sys.version_info[0] >= 3:
+    import PySimpleGUI as sg
+else:
+    import PySimpleGUI27 as sg
+
+"""
+    Simple field validation
+    Input field should only accept digits.
+    If non-digit entered, it is deleted from the field
+"""
+
+layout = [[sg.Text('Enter digits:')],
+            [sg.Input(do_not_clear=True, enable_events=True,  key='_INPUT_')],
+            [sg.Button('Ok', key='_OK_'),sg.Button('Exit')]]
+
+window = sg.Window('Window Title').Layout(layout)
+
+while True:             # Event Loop
+    event, values = window.Read()
+    if event in  (None, 'Exit'):
+        break
+    if not len(values['_INPUT_']):      # if field is empty ignore
+        continue
+    if values['_INPUT_'][-1] not in ('0123456789'):                 # if last char entered not a digit
+        window.Element('_INPUT_').Update(values['_INPUT_'][:-1])    # delete last char from input
+window.Close()