How do I enable GDI+

The Language Reference states:

New Constructor
To create a Picture with an alpha channel, use the new constructor that omits the Depth parameter:
Constructor(width As Integer, height As Integer)

Picture.Constructor(width as Integer, height as Integer)
On Windows, alpha channels require GDI+ to be enabled. On OS X, you must build using Cocoa. Otherwise you will get a PlatformNotSupportedException

How do I enable GDI+ on my Windows XP SPIII (running in VirtualBox) ?

In the IDE it’s under the Windows build settings. You can also use App.UseGDIPlus = True in your code. This is a Xojo setting that’s specific to your app; you don’t need to change anything in Windows.

I asked because I had this error: PlatformNotSupportedException

and the highlighted line was:
Dim OffscreenPict As New Picture(250,250)

On the other hand, “Use GDI Plus” is off in that project. I do not know why; I am quite certain that I do not change that value.

I checked with creating a brand new project and “Use GDI Plus” is off by default (here).

Thank you for your kind answer.