>>>Is there any difference between these two functions - Dragan's anticipated comments aside - or advantage of one over the other?
>>>

>>>IF VARTYPE( THISFORM.tmrCheckMousePosition ) = 'O'
>>>

>>>

>>>IF PEMSTATUS(THISFORM.tmrCheckMousePosition,'O',3)
>>>

>>
>>Are equal for not protected or hidden properties, but :
>>
>>

>>CLEAR
>>X = CREATEOBJECT("XX")
>>? PEMSTATUS(m.x,"property",5)
>>? VARTYPE(x.undef)				&& This work !!!!
>>? VARTYPE(x.property) 			&& Expected : "U" too ; Error ! this is a BUG
>>
>>DEFINE CLASS xx as Custom
>>	PROTECTED property 
>>	
>>	PROCEDURE Init
>>	? PEMSTATUS(m.this,"property",5),VARTYPE(this.property)
>>	
>>ENDDEFINE
>>

>
>Why did it error on this line?
>

>? VARTYPE(x.property) 			&& Expected : "U" too ; Error ! this is a BUG
>

As Fabio wrote, it's a bug, Vartype() errors on not existing properrties. Try
?Type('_vfp.alias') && 'U'
?Vartype(_vfp.alias) && Error