XnView Software

please make possible to delete files (with no confirmation) in viewer mode (same as XnView does)

You can delete in view mode

i see. in Viewer mode only File menu - Delete works
but is it possible to assign Del key?

+1 for this request. With every version being released, I hope to see this in the change log.

With Linux file menu delete is working, but hitting the "Del" key triggers no actions in the image view. Enabling the "Del" key in the image view would speed up the process of sorting out pictures a lot.

You can.
Goto settings--interface--shortcuts, and in view mode section assign "Delete..." item to Del key.

This request was made some time ago and to me it seems it is fullfilled, but...

it is doing the file delete even if I have made a selection.
I want to delete the selection and not the entire file.

My suggestion:
If the image is without alpha, then it should fill the selected area with the background color, or white, as the old xnview does.
If it got alpha, then it should set the selected area to become invisible.
Only if there is no selection, it should delete the entire file

Please check XnViewMP 0.48