Bug in both spinboxes

Platform
Linux
Platform details
64bit gentoo system, but got the same bug, on windows 32 bit and on gentoo linux 4.6
Compilers
GCC
Compiler details
x86_64-pc-linux-gnu-4.3.2
on windows it was msvc
Subject
bug in both spinboxes
Steps to reproduce / test case
1. compile and start the mini project
2. position the cursor (with the mouse to a position to the right of the most left thousand delimiter)
3. press the zero digit (the digit will be inserted and the delimiters are gone)
4. now click into the other box to change the focus
5. the value changes back to what it was before we inserted a zero
More information
I connected the valueChanged signal and even this one is not working as soon as I insert the digit