B4J Question mainform change position

at my program I have
#MainFormWidth: 600
#MainFormHeight:400
At the starting the mainform shows at the center of the screen
how can I change the position to 0,0 of the screeen? something like mainform.left=0:mainform.height=0
how can i get the width and the height of the screen?
I want to write like vb6 as follow

myform.left=0
myform.top=0
myform.width=screen.width
myform.height=screen.height

and

myform.maximize=true or myform.minimize=true

thank

Kalarakis
Creta
Greece