refactor(xgamma): use _comp_compgen -P for -display:*.*

Author: akinomyoga

completions/xgamma

@@ -32,8 +32,8 @@ _comp_cmd_xgamma()
                 # local screen numbers
                 local t screens=$(xrandr --query 2>/dev/null | command sed -ne \
                     '/^Screen /s|^Screen \{1,\}\(.*\):.*$|\1|p' 2>/dev/null)
-                t="${cur#:}"
-                _comp_compgen -c "${cur##*.}" -- -P "${t%.*}." -W '$screens'
+                cur="${cur#:}"
+                _comp_compgen -P "${cur%.*}." -- -W '$screens'
             elif [[ $cur != *:* ]]; then
                 # complete hostnames
                 _comp_compgen_known_hosts -c -- "$cur"