FF - an interesting moment, which did not know before
Immediately to the point.
In the form he made such a construction for autocomplex (two inputs inside one label):
label -> input type=hidden -> input type=text
')
And I found that in this situation the text field could not get the focus after clicking the mouse (the cursor appears and disappears immediately, if you start typing from the keyboard - nothing happens). After I found out: if both inputs are text-based, it is clearly visible what is being done: when you click on the second input (mouseDown), the cursor appears there, but when you click mouse, it immediately jumps to the first input. Previously, I did not know this, and the search did not help very much (maybe, of course, I looked badly), so I decided to publish it.
Yes, by the way, if you move around the form using Tab, everything is fine, the focus is not lost. And also - there is no such effect in chrome, I haven't looked anywhere else.