Masks and Atlas building
All gfx files (objects and character/enemies etc) needs a mask and need to be added to an atlas to improve render performance.
No worries, both is an automatic process and will be done as soon as you restart your editor.
How it works
On startup, the editor checks if something has changed in the folder of your mod. If this is the case the editor will create all the masks you need and add all the new gfx to the atlas. This may take a few seconds depending on your system and how many assets your project has.
Improtant:New assets are only availble to you in the editor if you did this atlas packing (restart of editor) after adding them to your folder.