Docstrings, Warnings added to Window so that bad titles and bad layout types are warned. It's crude but will be helpful. Also first time using this warnings module. Hope it's OK! New Demo Program - invisible elements shows using a column for visibility

DemoPrograms/Demo_Invisible_Elements.py

@@ -0,0 +1,27 @@
+import PySimpleGUI as sg
+
+"""
+    Demonstrates that using a Column Element to make groups of Elements appear and disappear
+    will cause the layout of the elements in the column to remain as they were.  If each individual element
+    were made invisible and then visible, then tkinter puts EACH ELEMENT on a separate row when it is made
+    visible again.  This means a row of 6 elements will become a column of 6 elements if you make each of them
+    visible one at a time.
+
+"""
+
+layout = [[sg.Column([[sg.Text('My Window')],[sg.Input(key='_IN_'), sg.B('My button', key='_OUT_')]], key='_COL_')],
+            [sg.Button('Invisible'), sg.B('Visible'), sg.Button('Exit')]]
+
+window = sg.Window('Window Title', layout)
+
+while True:             # Event Loop
+    event, values = window.Read()
+    print(event, values)
+    if event in (None, 'Exit'):
+        break
+    if event == 'Invisible':
+        window.Elem('_COL_').Update(visible=False)
+    elif event == 'Visible':
+        window.Elem('_COL_').Update(visible=True)
+
+window.Close()

PySimpleGUI.py

@@ -2748,7 +2748,7 @@ class Graph(Element):
         self.BottomLeft = graph_bottom_left
         self.TopRight = graph_top_right
         # self._TKCanvas = None               # type: tk.Canvas
-        self._TKCanvas2 = None  # type: tk.Canvas
+        self._TKCanvas2 = self.Widget = None  # type: tk.Canvas
         self.ChangeSubmits = change_submits or enable_events
         self.DragSubmits = drag_submits
         self.ClickPosition = (None, None)
@@ -3697,16 +3697,16 @@ class Slider(Element):
 
 
 # ---------------------------------------------------------------------- #
-#                          TkScrollableFrame (Used by Column)            #
+#                          TkFixedFrame (Used by Column)                 #
 # ---------------------------------------------------------------------- #
 class TkFixedFrame(tk.Frame):
-    """ """
+    """
+    A tkinter frame that is used with Column Elements that do not have a scrollbar
+    """
     def __init__(self, master, **kwargs):
         """
-
-        :param master:
-        :param **kwargs:
-
+        :param master: (tk.Widget) The parent widget
+        :param **kwargs: The keyword args
         """
         tk.Frame.__init__(self, master, **kwargs)
 
@@ -3730,17 +3730,17 @@ class TkFixedFrame(tk.Frame):
 #                          TkScrollableFrame (Used by Column)            #
 # ---------------------------------------------------------------------- #
 class TkScrollableFrame(tk.Frame):
-    """ """
+    """
+    A frame with one or two scrollbars.  Used to make Columns with scrollbars
+    """
     def __init__(self, master, vertical_only, **kwargs):
         """
 
-        :param master: ????????????????????????
-        :param vertical_only: ????????????????????????
-        :param **kwargs:
-
+        :param master: (tk.Widget) The parent widget
+        :param vertical_only: (bool) if True the only a vertical scrollbar will be shown
+        :param **kwargs: The keyword parms
         """
         tk.Frame.__init__(self, master, **kwargs)
-
         # create a canvas object and a vertical scrollbar for scrolling it
         self.vscrollbar = tk.Scrollbar(self, orient=tk.VERTICAL)
         self.vscrollbar.pack(side='right', fill="y", expand="false")
@@ -5000,6 +5000,12 @@ class Window:
         self.TransparentColor = transparent_color
         self.UniqueKeyCounter = 0
         self.DebuggerEnabled = debugger_enabled
+
+        if type(title) != str:
+            warnings.warn('Your title is not a string.  Are you passing in the right parameters?', UserWarning)
+        if layout is not None and type(layout) != list:
+            warnings.warn('Your layout is not a list... this is not good!')
+
         if layout is not None:
             self.Layout(layout)