KeyPressFilter with whitespace

Hello there,

I'm trying to inherit TextItem to create TimeIntervalItem that accepts input in format (eg. 1w 5d 1h 23m). I'm using keyPressFilter String as: "[0-9wdhm.]" this works fine for digits and (wdhm chars), but I can't tell the item to accept white spaces as well. I've tried "\s" and literal space " " both doesn't work.
Any suggestions?

Regards,

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<b>UPDATE</b>
It worked! "[0-9wdhm\\s]" works however It didn't work earlier don't know why. Thanks anyway.