Description of problem:
30 seconds after login,  started dnfdragora gui - was all black after a minute it turned white and then disappeared!
Started it again, appears to be ok,  It does seem to crash every now & then. 

Version-Release number of selected component:
dnfdragora-gui-1.0.1-5.git20170505.2a3b056.fc26

Additional info:
reporter:       libreport-2.9.1
cmdline:        /usr/bin/python3 /bin/dnfdragora-updater
crash_function: _handle_dbus_error
exception_type: dnfdaemon.client.DaemonError
executable:     /bin/dnfdragora-updater
kernel:         4.11.11-300.fc26.x86_64
runlevel:       N 5
type:           Python3
uid:            1000

Truncated backtrace:
__init__.py:250:_handle_dbus_error:dnfdaemon.client.DaemonError: g-io-error-quark: GDBus.Error:org.baseurl.DnfSystem.LockedError: dnf is locked by another application (36)

Traceback (most recent call last):
  File "/usr/lib/python3.6/site-packages/pystray/_base.py", line 236, in inner
    callback(self)
  File "/usr/lib/python3.6/site-packages/pystray/_base.py", line 320, in __call__
    return self._action(icon, self)
  File "/usr/lib/python3.6/site-packages/pystray/_base.py", line 414, in wrapper1
    return action(icon)
  File "/usr/lib/python3.6/site-packages/dnfdragora/updater.py", line 109, in __run_dnfdragora
    return self.__run_dialog({})
  File "/usr/lib/python3.6/site-packages/dnfdragora/updater.py", line 104, in __run_dialog
    self.__main_gui = ui.mainGui(args)
  File "/usr/lib/python3.6/site-packages/dnfdragora/ui.py", line 214, in __init__
    rpm_groups = self.backend.GetGroups()
  File "/usr/lib/python3.6/site-packages/dnfdragora/basedragora.py", line 50, in backend
    return self.get_root_backend()
  File "/usr/lib/python3.6/site-packages/dnfdragora/basedragora.py", line 77, in get_root_backend
    self.backend.ExpireCache()
  File "/usr/lib/python3.6/site-packages/dnfdaemon/client/__init__.py", line 401, in ExpireCache
    rc = self._run_dbus_async('ExpireCache', '()')
  File "/usr/lib/python3.6/site-packages/dnfdaemon/client/__init__.py", line 293, in _run_dbus_async
    result = self._get_result(data)
  File "/usr/lib/python3.6/site-packages/dnfdaemon/client/__init__.py", line 277, in _get_result
    self._handle_dbus_error(user_data['error'])
  File "/usr/lib/python3.6/site-packages/dnfdaemon/client/__init__.py", line 250, in _handle_dbus_error
    raise DaemonError(str(err))
dnfdaemon.client.DaemonError: g-io-error-quark: GDBus.Error:org.baseurl.DnfSystem.LockedError: dnf is locked by another application (36)

Local variables in innermost frame:
msg: ''
exc: ''
err: GLib.Error('GDBus.Error:org.baseurl.DnfSystem.LockedError: dnf is locked by another application', 'g-io-error-quark', 36)
self: <dnfdragora.dnf_backend.DnfRootBackend object at 0x7fdde8fecf98>

Potential duplicate: bug 1461072