Checked it a little bit and what i have so far:
is actually MAP EDITOR.
you can load IFF images and convert them to .gra format to use in the program.
starts a Deluxe paint clone program to paint graphics.
you can start a file manager to manipulate your disks (copy, erase etc)
Edit skeleton disk
lets you edit an already made game with this program, change graphics, maps etc. Use shoot em up disk and try Load level, Load stats then Edit stats, attack waves
. Looks really complicated. Everything is text, no icons
starts a text editor
you can make animations by grabbing your sprites, define speed of animation, hotspot etc.
Looks like you need the platform skeleton disk to make a platform in example, you cannot make from the master disk direct, you just edit the existing game in the skeleton disk. With Adventure skeleton disk you can make a Dizzy style game.