Is there a way to set the wallpaper with one click

[danbuz]

So to be brief, I decided to replace (not remove) nautilus with pcmanfm, and all seems to work fine except that I'm not able to set the background.
When I choose the wallpaper from pcmanfm it is ok, until I go to activities on preview mode, and there is other wallpaper ( the one set from background settings).
What I did is setting manually the same background from settings and with pcmanfm with right click, but than the one is stretched and the other is centered.

Is there a way set it only with right click on pcmanfm for both previews?

Thanks in advance!