Every file in folder have the same icon like there wasn't program for opening it.
I have installed programs like GPicView, LXMusic, Audacious

But when i'm trying to open any file I get "Open with..." dialog window

I can open it when i'm choosing the program from the second tab but i want to do this by doubleclick.
Default program is not updated and i have to do it everytime i want to open file.