Help : maximized windows

I am designing a multi platform application and I am using wx.NET.

One of my problem is to start my frame maximized because when I try this :

 

public MainFrame()

: base(null, -1, "LetItBurn!",wxDefaultPosition, new Size(800,600),
wxMAXIMIZE )

 

My frame is maximized but too much because the title bar, the minimize and
maximize box are out

Of the screen.

 

My second problem comes from images in my toolbar because on Windows it
seems to display

Correctly but on linux there is no transparent mask on the images so I see a
black rectangle

Around my images.