Bug report - changing boxsizer orientation

Hi, when I change the orientation of a boxsizer from HORIZONTAL to VERTICAL, I see an error dialog appear.

Here is the info:

ERROR   : None
An unexpected error occurred!

Exception type:      <class 'IndexError'>
Exception details:   list index out of range

Application stack traceback:
  File "/usr/local/lib/python3.7/site-packages/wx/core.py", line 3240, in <lambda>
    lambda event: event.callable(*event.args, **event.kw) )
  File "wxGlade/edit_sizers/edit_sizers.py", line 592, in change_sizer
    elem = szr.sizer.widget.GetChildren()[szr.pos]

Date and time:       2019-01-06T22:24:19.044063
Python version:      3.7.2
wxPython version:    4.0.3
wxWidgets platform:  __WXMAC__
wxGlade version:     0.9.0b3


I also noticed this sentence in the "How to Report a Bug" tab: - What did you? May you want to include a screenshot.

It should be changed to: - What you did. You may wish to include a screenshot.

Thank you.