How to center dlangui on screen

[greatsam4sure]

I am learning Dlang and Dlangui.

I encounter, a little problem on:

  how to center dlangui window on screen.

How to set the window width and height outside the constructor

How to maximize and minimize the window using code.

How to set global font for the application.  The font display is 
not too nice.

I have check online, the documentation  and available tutorial to 
no help

Thanks in advance