Reproducible: always

Steps To Reproduce

1. Click search icon in front of the megabar
2. Type [Keyword of Keyword search][a space][search words]
3. Hit Enter

Actual Results:
Page result is "[Keyword of Keyword search][a space][search words]" with default search engine

Expected Results:
"[search words]" with Keyword search

How to perform Keyword search from "search icon in front of the megabar"?

Before Bug 1589836 , [Keyword of Keyword search][a space][search words] works as expected.
This interface makes me be confused.

The search icon makes the address bar work like the search bar, where keyword searches don't work either. It's the same as using Accel+K with the search bar hidden.

Strange thing happens

When I make miss type at step 2
So, I will correct the input
Select All and hit Del key
--- erased whole the input, it' OK
Type [Keyword of Keyword search][a space][search words] again
Hit Enter

Actual Results:
Keyword search is performed as expected

It is strange for me.
Why "Select All and hit Del key" changes the behavior?

I agree with Dao, the scope here is to enter a Search Mode. In serch mode whatever you type is expected to be sent to the search engine. The existence of the "?" char is just a temporary solution until bug 1590732 is implemented, and the current status looks unconsistent just because part of the UI is missing (the part showing search mode is enabled).

Long term this won't be an issue.

Ahhhh, "? " is pre-filled by default.

I think it should be highlighted "@Google " instead of simple "? ".
I filed a new Bug 1590785