« Open with » vs. file and app' association?


Let’s say I have a png file on my desktop. When I double-click it, file is opened through a default photo app’ ( gthumb ) and it’s ok.

Now, instead of double-click, I may use right-click « open with » to open my png file through the Gimp. Works ok too.

Then if I double-click again on that file, it will get opened through …the Gimp ( last app’ used for that kind of file ).

Is it intended behavior ? Or where do I « permanently » set the default app’ for png files ?

Ok… my mistake… In « settings » and « default applications » photos were set to Gimp…