Removing the close tab button when too many tabs are open (FF vs Chrome behavior)

When I have too many open tabs, the close tab button disappears
for every tab except the one currently being displayed. If I want to
close another tab, I have to click on it first before I can close it.
Obviously, it is kind of annoying to have to go through this extra
step.

Now, this behavior is the same in both Firefox and Chrome, except that
in the latter I can have way more tabs open before the close tab button
disappears (on my Macbook Pro, with 1680x1050 display resolution,
and both browsers maximized, I can have about 11 open tabs in
Firefox, and about 26 open tabs in Chrome).

For smaller window sizes, the number of tabs I can have open is even
smaller. It regularly happens to me that the close tab button
disappears in Firefox with only 6 tabs open. In Chrome, on the other
hand, I rarely, if ever, run into this problem.

Wouldn't it be nice to raise the number of tabs that can be opened in 
Firefox before the close tab button disappeared?