In the keypress event of a textbox I put :

------------------------------------------------------------------
LPARAMETERS nKeyCode, nShiftAltCtrl

NODEFAULT
local lnant_start

if nKeyCode = 45
lnant_start = this.SelStart
this.SelStart = 0
this.SelLength = lnant_start
this.SelText = transform(val(left(alltrim(str(val(this.SelText))), 4)), "@L 9999")
this.SelStart = 4
endif

dodefault()
-------------------------------------------------------------------

This.inputmask = 9999-99999999
This.Width = 14
This.MaxLength = 12
This.ControlSource = myfile.myfield (Numeric 12)

The idea is to fill with 0's the beginning of the first 4 characters when the user presses '-'.
When I run the form the code does it's work OK but when I press < ENTER> nothing happens.

Any ideas???