Issues in demos

- [x] examples/demo/Standard_Editors/CompoundEditor_demo.py
Gives traceback error when alphabets are clicked (from second click onwards).
Traceback (most recent call last):
File "/Users/sgovindaraju/.edm/envs/traitsui_tutorial/lib/python2.7/site-packages/traitsui/wx/range_editor.py", line 251, in update_object_on_enter self._convert_to_slider(self.value))
File "/Users/sgovindaraju/.edm/envs/traitsui_tutorial/lib/python2.7/site-packages/traitsui/wx/range_editor.py", line 297, in _convert_to_slider
ivalue = int((float(value - self.low) /
TypeError: unsupported operand type(s) for -: 'str' and 'int'

- [x] examples/demo/Standard_Editors/DirectoryEditor_demo.py
Traceback when closing or when OK is clicked and does not close.
Traceback (most recent call last):
File "/Users/sgovindaraju/.edm/envs/traitsui_tutorial/lib/python2.7/site-packages/traitsui/wx/ui_live.py", line 344, in _on_close_page
self._on_cancel(event)
File "/Users/sgovindaraju/.edm/envs/traitsui_tutorial/lib/python2.7/site-packages/traitsui/wx/ui_live.py", line 398, in _on_cancel
self.close(wx.ID_CANCEL)
File "/Users/sgovindaraju/.edm/envs/traitsui_tutorial/lib/python2.7/site-packages/traitsui/wx/ui_live.py", line 333, in close
ui.finish()
File "/Users/sgovindaraju/.edm/envs/traitsui_tutorial/lib/python2.7/site-packages/traitsui/ui.py", line 283, in finish
self.reset(destroy=False)
File "/Users/sgovindaraju/.edm/envs/traitsui_tutorial/lib/python2.7/site-packages/traitsui/ui.py", line 325, in reset
editor.dispose()
File "/Users/sgovindaraju/.edm/envs/traitsui_tutorial/lib/python2.7/site-packages/traitsui/wx/file_editor.py", line 125, in dispose
panel.Bind(wx.EVT_BUTTON, self._button.GetId(), None)
File "/Users/sgovindaraju/.edm/envs/traitsui_tutorial/lib/python2.7/site-packages/wx/_core.py", line 4224, in Bind
assert handler is None or callable(handler)
AssertionError

- [x] examples/demo/Standard_Editors/FileEditor_demo.py
Similar to DirectoryEditor_demo.py

- [ ] examples/demo/Standard_Editors/FontEditor_demo.py
Font changes but the size does not. (Corran) Additionally, when I try to edit the simple version I get an immediate hard crash when I click on the editor:
```
2019-08-16 06:54:39.541 Python[39188:2656896] -[NSView resetFlags]: unrecognized selector sent to instance 0x7fa99c657c20
Error in atexit._run_exitfuncs:
Traceback (most recent call last):
File "/Users/cwebster/.edm/envs/traitsui-test-2.7-wx/lib/python2.7/atexit.py", line 24, in _run_exitfuncs
func(*targs, **kargs)
PyAssertionError: C++ assertion "GetEventHandler() == this" failed at /Users/vagrant/workspace/Buildsystem/test/pisi/tmp/wxPython-3.0.2.0-7/work/wxPython-src-3.0.2.0/src/common/wincmn.cpp(478) in ~wxWindowBase(): any pushed event handlers must have been removed
Error in sys.exitfunc:
Traceback (most recent call last):
File "/Users/cwebster/.edm/envs/traitsui-test-2.7-wx/lib/python2.7/atexit.py", line 24, in _run_exitfuncs
func(*targs, **kargs)
wx._core.PyAssertionError: C++ assertion "GetEventHandler() == this" failed at /Users/vagrant/workspace/Buildsystem/test/pisi/tmp/wxPython-3.0.2.0-7/work/wxPython-src-3.0.2.0/src/common/wincmn.cpp(478) in ~wxWindowBase(): any pushed event handlers must have been removed
```

- [ ] examples/demo/Standard_Editors/TableEditor_demo.py
Not sure what the behavior is. The bottom part disappears when some row is clicked. The first is a screenshot just after launch and the second is after the second row is clicked.


- [ ] examples/demo/Standard_Editors/TupleEditor_demo.py
The color does not change in sync on first attempt. For example, changing color on 'simple' does not change color on 'complex'. Now, if I change color on 'complex' (it works), and if I do it on 'simple' again, it works.

- [ ] examples/tutorials/tutor.py
When I browse to Python Source Browser Example and click on Demo button, I get errors:
Traceback (most recent call last):
File "/Users/sgovindaraju/.edm/envs/traitsui_tutorial/lib/python2.7/site-packages/traitsui/qt4/tabular_model.py", line 107, in data
q_color = QtGui.QColor(color)
TypeError: arguments did not match any overloaded call:
QColor(Qt.GlobalColor): argument 1 has unexpected type 'Colour'
QColor(int): too many arguments
QColor(Any): argument 1 has unexpected type 'Colour'
QColor(): argument 1 has unexpected type 'Colour'
QColor(int, int, int, alpha: int = 255): argument 1 has unexpected type 'Colour'

- [ ] examples/demo/Standard_Editors/TreeEditor_demo.py
In WX, this gives the message
03:59:54 PM: Warning: iCCP: known incorrect sRGB profile
In QT, changing any entry gives an error:
Traceback (most recent call last):
File "/Users/sgovindaraju/.edm/envs/tutorials_qt/lib/python2.7/site-packages/traitsui/qt4/ui_panel.py", line 343, in sizeHint
if ui.view.width > 0:
AttributeError: 'NoneType' object has no attribute 'width'
Traceback (most recent call last):
File "/Users/sgovindaraju/.edm/envs/tutorials_qt/lib/python2.7/site-packages/traitsui/qt4/ui_panel.py", line 343, in sizeHint
if ui.view.width > 0:
AttributeError: 'NoneType' object has no attribute 'width'

- [x] examples/demo/Advanced/Adapted_tree_editor_demo.py
In WX, trying to close the window gives an exception
Traceback (most recent call last):
File "/Users/sgovindaraju/.edm/envs/tutorials_wx/lib/python2.7/site-packages/traitsui/wx/ui_live.py", line 344, in _on_close_page
self._on_cancel(event)
File "/Users/sgovindaraju/.edm/envs/tutorials_wx/lib/python2.7/site-packages/traitsui/wx/ui_live.py", line 398, in _on_cancel
self.close(wx.ID_CANCEL)
File "/Users/sgovindaraju/.edm/envs/tutorials_wx/lib/python2.7/site-packages/traitsui/wx/ui_live.py", line 333, in close
ui.finish()
File "/Users/sgovindaraju/.edm/envs/tutorials_wx/lib/python2.7/site-packages/traitsui/ui.py", line 283, in finish
self.reset(destroy=False)
File "/Users/sgovindaraju/.edm/envs/tutorials_wx/lib/python2.7/site-packages/traitsui/ui.py", line 325, in reset
editor.dispose()
File "/Users/sgovindaraju/.edm/envs/tutorials_wx/lib/python2.7/site-packages/traitsui/wx/file_editor.py", line 125, in dispose
panel.Bind(wx.EVT_BUTTON, self._button.GetId(), None)
File "/Users/sgovindaraju/.edm/envs/tutorials_wx/lib/python2.7/site-packages/wx/_core.py", line 4224, in Bind
assert handler is None or callable(handler)
AssertionError

- [ ] examples/demo/Standard_Editors/FileEditor_demo.py
The simple editor greys out file, so files cannot be selected. custom works fine.