New binding and clarification in comment.

tridactyl/tridactylrc

@@ -19,7 +19,7 @@ bind ;c hint -c [class*="expand"],[class="togg"]
 command ba back
 command fo foward
 
-" restore bookmarks
+" restore buildin bookmarks
 unbind <C-b>
 
 " use h/l to cycle though tabs.
@@ -34,6 +34,8 @@ bind n findnext 1
 bind N findnext -1
 bind ,<Space> nohlsearch
 
+bind <Space> fillcmdline_notrail
+
 " Text to speech is broken on all of my firefox instances. I'll just use my
 " own.
 unbind ;r