Aspect ratio of video playback becomes invalid, if extended desktop is used

Steps to reproduce:
1. Start mythtv frontend with single display on.
2. Use xrandr to extend desktop to cover two displays. (The displays have different aspect ratios.)
3. Go to media library and start playback.

Or:
1. Use xrandr to extend desktop to cover two displays. (The displays have different aspect ratios.)
2. Start mythtv frontend. It seems to open in the primary display.
3. Go to media library and start playback.

Expect aspect ratio of the video to be correct (as it was with single display).
But it is different. Like vertical fill and horizontal fill even if only horizontal fill is selected in settings.

Workaround:
Set Appearance > Monitor aspect ratio in Setup of MythTV Frontend.

ProblemType: Bug
DistroRelease: Ubuntu 15.10
Package: mythtv-frontend 2:0.27.1+fixes.20140624.aa822f5-0ubuntu6
ProcVersionSignature: Ubuntu 4.2.0-18.22-generic 4.2.3
Uname: Linux 4.2.0-18-generic x86_64
NonfreeKernelModules: nvidia
ApportVersion: 2.19.1-0ubuntu5
Architecture: amd64
CurrentDesktop: XFCE
Date: Fri Nov 27 18:08:24 2015
EcryptfsInUse: Yes
InstallationDate: Installed on 2015-11-21 (5 days ago)
InstallationMedia: Xubuntu 15.10 "Wily Werewolf" - Release amd64 (20151021)
Installed_mythtv_dbg: 2:0.27.1+fixes.20140624.aa822f5-0ubuntu6
MythTVDirectoryPermissions:
 total 8
 drwxrwsr-x 2 mythtv mythtv 4096 marra 22 15:57 bare-client
 drwxr-xr-x 2 root root 4096 elo 24 02:10 videos
SourcePackage: mythtv
UpgradeStatus: No upgrade log present (probably fresh install)