To enable or disable "Advertise Firefox compatibility" in SeaMonkey 2.1 or later versions:

1.  On the SeaMOnkey menubar, select [Edit > Preferences].  

2.  On the Preferences window, select [Advanced > HTTP Networking].  

3.  On the HTTP Networking pane
	a.  checking the checkbox for "Advertise Firefox compatibility" enables the feature
	b.  unchecking the checkbox disables the feature.