clicks sometimes cause resize

This has been mentioned here before, recently.  Sometimes clicking at
random places in an app like firefox causes the cursor to switch to a
cross and then moving the mouse resizes the window, without the button
being held down.  Obviously a bug.

Anyhow, I recall no one could pin down exactly how to reliably
reproduce it on demand.  I just did:

In FF57 open a couple of tabs.  Click the empty area to the right of
the tabs, to the right of the "+" sign.  Then click one of the tab
titles.  This causes the "click turns into a resize drag" bug
instantly, every time.  At least for me on Fedora 26 anyhow.

Anyone have a fix yet?

-- 
Sawfish ML