Transparent windows

[Enrico Sersale]

As I've done for [selectFile:inFileViewerRootedAtPath:] and other
NSWorkspace methods, I've implemented, in GWorkspace,
[openFile:fromImage:at:inView:] and [slideImage:from:to:].

This means that, if you want, these NSWorkspace methods can be changed to
use [self _workspaceApplication].

Actually, I'm using [slideImage:from:to:] to move an icon from its view to
the fiend icon of the application that will open it (as on openstep).

To do this I use a borderless window that contains the icon to move. The
problem is that this window uses [NSColor controlColor] for the
background and this results in a gray border around the icon.

As I've asked regarding the transparent images, would it be very difficult
to add transparency to the windows?

I've seen that NSWindow has a [setAlphaValue:] method but the value you
set is not used...