- # Xdefaults uses ! as comment instead of #. tmp file necessary because of
- # different implementations of `sed -i`.
- sed 's/^#/!/' Xdefaults > Xdefaults.tmp
- mv Xdefaults.tmp Xdefaults
+ # Xresources uses ! as comment instead of #.
+ sed_i 's/^#/!/' Xresources
+ # Use urxvt's pseudo-transparency if neither compton nor xcompmgr are
+ # available. Better than nothing.
+ if ! installed compton && ! installed xcompmgr; then
+ echo 'Xresources: no compton found, enabling pseudo-transparency'
+ sed_i 's/^Rxvt\*background: \[/!&/' Xresources
+ sed_i 's/^!NO_COMPTON //' Xresources
+ fi