Double-click on a file opens the associated program

[Wolfen]

Hello,

I've just installed XnViewMp 0.72 (Linux), everything is fine except that when I double-click on a picture in the browser view it opens the picture with the associated program, instead of opening it in a tab inside XnView.

Basically when I double click a picture it does "Open with Associated program (F3)" instead of "Open (Ctrl+O)".

Is it normal?

[xnview]

strange, which thumbnail mode do you use? do you use catalog db?