[Bug 41511] New: gray square on tab

https://bugs.winehq.org/show_bug.cgi?id=41511

Bug ID: 41511
           Summary: gray square on tab
           Product: Wine
           Version: 1.9.20
          Hardware: x86-64
                OS: Linux
            Status: UNCONFIRMED
          Severity: major
          Priority: P2
         Component: -unknown
          Assignee: [e-mail]
          Reporter: [e-mail]
      Distribution: ---

Created attachment 55873
  --> https://bugs.winehq.org/attachment.cgi?id=55873
picture1

When I open notepad++ , there is a gray square on top of the first tab
picture1 : shows the square

If I move the window little up and on the left, the square is now in the
document 
picture2 : shows the square on the document

picture3 : shows the square bigger