About Multi-video Player
App is designed to play back up to 4 videos simultaneously. Videos can be easily rearranged on the screen. App provides common for all videos basic playback control like play, pause etc. In addition, every video can be individually hidden, paused or muted.
There is file open and playback control buttons on the button of app screen.
What is unique about playback control panel is the set of color, one per video, lines each one is representing corresponding video
timeline, every time new video is entering the playback black color assigned to the video by default.
Playback control panel also has 
button to toggle all videos control panels visibility.
Every video has dedicated control panel allowing put video in pause or back in play, change
this video volume and remove this video from playback.
Every video's control panel also allows user to assign this video allies. User can also hide and show
back this video without playback interruption. Video frame color selector allows user to change color of video frame and this video timeline.
Leftmost coner of every video contrtol panel is where user changes position this video on the screen in respect to
all other videos in playback. For video to be displayed it must have certain position on the screen - newly opened video has no such a location
by default and displays "?" as a warning.
Double click on the leftmost coner invokes pretty unique user dialog to select this video position on the screen.
There are certain pretty obvious limitations for rearranging videos, e.g. there only one video in the center is allowed, etc.