Can't enter negative values in to SpinBox

I can't enter negative values in to SpinBox (MIN is < 0) by typing (or pasting): when I press minus sign then minus sign appears but then every digit I press is ignored (tried booth EN and LT keyboard layouts). I can only get negative values by scrolling in SpinEdit.

I tested this with Qt-Designer: created Window, placed SpinEdit and tried change MIN value in PropertyEditor but no success - I only can get negative value by scrolling. But then in Preview I can't type negative values in SpinBox - scroll is only solution.

I noticed that minus sign entered through keyboard and "standard" minus sign which you get if you scroll to negative values visually differs (screenshot attached: PropertyEditor of SpinBox in Qt-Designer).