[Bug 44979] New: Extra system title bar should not be added around Steam

https://bugs.winehq.org/show_bug.cgi?id=44979

Bug ID: 44979
           Summary: Extra system title bar should not be added around
                    Steam
           Product: Wine
           Version: 3.6
          Hardware: x86
                OS: Linux
            Status: UNCONFIRMED
          Severity: normal
          Priority: P2
         Component: -unknown
          Assignee: [e-mail]
          Reporter: [e-mail]
      Distribution: ---

Created attachment 61109
  --> https://bugs.winehq.org/attachment.cgi?id=61109
Screenshot of the main steam window

When I run Steam in any of the 3.x versions of wine, it adds an extra system
title bar around the steam window. See the attached image. There are 2 sets of
min/max/close buttons, etc. In 2.21 and prior, this does not occur.

This only happens for some of steam's windows. For instance, it does not occur
for the settings window. But, it does happen for the notifications window and
friends list window.

I am using Linux Mint 18.3 Cinnamon.