Try this

* Textbox KeyPress
LPARAMETERS nKeyCode, nShiftAltCtrl
IF Isnull(This.Value) AND Inlist(Chr(nKeyCode), "-1234567890.")
  This.Value = 0.00
ENDIF

BTW, you can use 'CTRL+0' shortcut to enter Nulls.

>Whenever you want to use a textbox for numeric data you can have a problem with null values.
>Ex. I have a form with a textbox whose inputmask is 999.99 and I set the value of the textbox to 0.
>I can go into the textbox and change the number and the vartype remains numeric. I also have a button on the form that sets the textbox.value to .null. Now if I try to change the data in the textbox say by typing 123.45
>the textbox.value type has changed to character. If I assign a controlsource then I can type a number in the textbox but it remains a character datatype.
>
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