Linux dialog has a weird behavior with keypad "special characters" (/, *, -, +)

Question

I have a specific problem that has been keeping me busy for a few weeks now. I use a python script that uses pythondialog (a dialog command wrapper for python) to request a config to the user. A bug has been opened mentionning that those characters (/,*,-,+) were closing the dialog instead of writing the character in the textbox. The "normal" characters (the same ones but not coming from the keypad) are working.

I've found that it is the normal behaviour of the dialog command, even without the python wrapper. (Like this)

dialog --title 'Message' --msgbox 'Hello, world!' 5 20

This is a problem occuring only when connecting with VNC. It is running with tightvnc.

Thank you,

L