I use the built-in browser. Why does OmegaEdit open certain files like xxx.png with external applications?
Because OmegaEdit is very good at handling all kinds of text files but cannot work with binary data like image files. There is no way to definitely tell a binary file from a text file so OmegaEdit uses file-extensions to make reasonable decisions. If you happen to have a xxx.png file that IS text then.. uh.. you should probably rename it to xxx.txt.