App freezes when loading large number of files

[rahmanshaber]

Overview Description: I noticed app freezes, sometimes the whole desktop when i try to select 100 files and select open with celluiod app from the context menu, after a while it unfreezes and start playing them.

Steps to Reproduce:

1. i need to play all the media in a folder, manually select them by going inside the folder
2. select open with celluiod app from the context menu

Actual Results: It freezes the app and sometime the desktop

Expected Results: it should load the files instantly

Version: 0.26, flatpak

Additional Information:

1. Better way to solve this is, if i select a folder and open with celluloid than it should go through all the media files in that folder and add them to the playlist.
2. And doing the playlist making should be done in separate thread.