Hi Everyone,
With Excel 2013 we also got new document windowing in Excel; Microsoft decided to make Excel behave the same as Word:
from MDI:
Image may be NSFW.
Clik here to view.
Clik here to view.

The Excel 2010 MDI interface
to SDI:
Image may be NSFW.
Clik here to view.
Clik here to view.

The new SDI interface of Excel 2013
This causes havoc when one shows a modeless userform which should stay on top of all Excel windows:
Image may be NSFW.
Clik here to view.
Clik here to view.

Excel 2013 SDI can cause a userform to disappear
I’ve devised a way to prevent this problem and written an article about how this was done.
Enjoy!
Regards,
Jan Karel Pieterse