Tk Library Source Code

I have an strange behavior that it invokes the command without stop. I write the next code in the wish8.6 console:
<pre class='verbatim'>
 ttk::spinbox .sb -from 0 -to 10000 -command [list ::danitest]
 grid .sb
 proc ::danitest {} {
    puts "inside"
    tkwait variable ::danivar
    puts "outside"
 }
</pre>
Then, I do a single click on any arrow. The command is invoked and I can read the message "inside". Now, the process is waiting to the change of my variable danivar. In this momment, I write in the console the next code:

<pre class='verbatim'>
 set ::danivar 1
</pre>

and when I press return I see that the message "outside" is shown, and some milliseconds later, the event is recalled (and I can read again the message "inside"). This behaviour doesn't stops.

I don't know if it is my fault or there is an error. I have the same behaviour if I use the command error instead of tkwait.