Hi,
Update code example.
You do get strange results with Masking, try the code below:- mask is bigger than the field. Fill the field slowly with "5"'s and see what happens.

PUBLIC oform1

oform1=NEWOBJECT("form1")
oform1.Show
RETURN

DEFINE CLASS form1 AS form

	DoCreate = .T.
	Caption = "Form1"
	AllowOutput = .F.
	Name = "Form1"

	ADD OBJECT text1 AS textbox WITH ;
		Alignment = 3, ;
		ControlSource = "test.numeric", ;
		InputMask = "###,###,###.##", ;	
		Left = 61, ;
		Top = 47, ;
		Name = "Text1"

	ADD OBJECT command1 AS commandbutton WITH ;
		Top = 46, ;
		Left = 186, ;
		Height = 27, ;
		Width = 84, ;
		Caption = "captureFocus", ;
		Name = "Command1"

	PROCEDURE Load
		create cursor test (numeric N(8,0))
		append blank
		? 'IS Blank',ISBLANK(numeric)
	ENDPROC

ENDDEFINE