Code review comment for lp:~fourdollars/unity-greeter/add-hidpi-support

I don't understand the purpose of:

var builder = new StringBuilder ();
builder.append ("xwininfo -root -tree");
builder.append ("| awk '{print $1}'");
builder.append ("| grep ^0x");
builder.append ("| while read id; do xprop -id $id; done");
builder.append ("| grep _XSETTINGS_SETTINGS > /dev/null");

Why do we need to do this?