It looks like vlc pops up a modal dialog on first launch, but it ends up behind the main vlc window.  If you alt-tab or otherwise switch to the dialog and dismiss it, everything works fine.

There is probably still a bug here in that the modal dialog shows up behind the main window.

Yeah, I recall seeing that same problem when I used VLC before in Crostini. But I'll look into it anyways because we're clearly doing something wrong with the ordering there (and I was just fixing something else in the code that I'd be suspicious of yesterday).

The following revision refers to this bug:
  https://chromium.googlesource.com/chromiumos/platform2/+/7c2b21a7feb775a24a2cffddb05914aec38da1b6

commit 7c2b21a7feb775a24a2cffddb05914aec38da1b6
Author: Jeffrey Kardatzke <jkardatzke@google.com>
Date: Sun Dec 09 08:48:21 2018

vm_tools: Fix window parenting for transient windows

This fixes a bug where we wouldn't always set the parent window
correctly for transient windows with X11. Sometimes the child was
realized before the parent. Sometimes the direct parent doesn't exist as
a wl_surface so we need to find an alternate.

BUG= chromium:910219 
TEST=Verified that VLC has dialogs on top and they stay there

Change-Id: I098ee22e66dcab4e7a438872b41007867743d8b0
Reviewed-on: https://chromium-review.googlesource.com/1368368
Commit-Ready: ChromeOS CL Exonerator Bot <chromiumos-cl-exonerator@appspot.gserviceaccount.com>
Tested-by: Jeffrey Kardatzke <jkardatzke@google.com>
Reviewed-by: David Reveman <reveman@chromium.org>

[modify] https://crrev.com/7c2b21a7feb775a24a2cffddb05914aec38da1b6/vm_tools/sommelier/sommelier.c

 Issue 915400  has been merged into this issue.