Search text not cleared when using the "Paste & Search" context menu.

Using latest nightly x64 versions (currently on 40.0a1) on Windows 8.1 and Searchbar Autosizer 3.1.1...

I have enabled the "Empty searchbar when a query is submitted" setting and it works just fine when I type something and then hit the enter button from my keyboard.

When I want to search for something that is copied on my clipboard though, I don't use my keyboard but instead use the mouse right-click -> Paste & Search. In this case, the search text is not cleared after submission.

This bug has been pestering me for some time now (could have been since nightly 38.0a1 or even before), but did not report it because I thought it was a known issue and somebody has already reported it. Well enough time has passed now and it seems that nobody else is having it because I don't see it reported.

Easy to reproduce:

1. Install Firefox (the bug might might not be present in the current 37.x stable version - install latest nightly).
2. Install Searchbar Autosizer.
3. enable the "Empty searchbar when a query is submitted" setting.
4. Type some text in the searchbar and hit the Enter key on your keyboard...

Expected behavior: search query submitted / search text cleared from the searchbar.
Actual behavior: search query submitted / search text cleared from the searchbar (works as expected)

5. Select some text and copy it on your clipboard.
6. Right-click with your mouse in the searchbar and select the "Paste & Search" option...

Expected behavior: search query submitted / search text cleared from the searchbar.
Actual behavior: search query submitted / search text NOT cleared from the searchbar