On arch linux default programs do not matter.
When I open a file I downloaded from my browser, whether its a pic, archive or otherwise, It always just opens the file in another browser, which downloads it again.
Text files are problematic too, they never open in the right text editor, it seems to change daily which one it defaults to.
I also cannot set my default browser, setting it does nothing and my default browser seems to have a mind of its own.
Today, it is firefox, other times it is seamonkey or mosaic.
I am not really sure what to do about this I have hit "set default" and set "open with this progam every time" in mate or kde a thousand times and it does not do anything.