Drawing Native OSX Windows with D

[Mike McKee via Digitalmars-d-learn]

On Saturday, 28 November 2015 at 14:05:37 UTC, Jacob Carlborg 
wrote:
> If you can't/don't want to go with the App Store then why not 
> the second option?

I'm coding an antivirus application for the Mac, using a 
third-party antivirus engine, in Qt/C++. It needs some things to 
run under high privileges. As far as I know, you can't do that 
with a DMG package, but can do it with a PKG package.

I've learned a tremendous amount about PKG packages (the docs are 
difficult), but the one thing that doesn't seem possible is to 
download a component from a remote URL with it except via a Perl 
or Bash script. The PKG flat format supports a way to call a 
preinstall and postinstall Perl or Bash script. The trouble with 
that technique, however, is that if you have a 30MB download that 
takes awhile, the installer screen sits at "Running Package 
Scripts..." for like 3 minutes (on 2Mbps DSL) and this can 
confuse the consumer into thinking the installer is hung up, when 
it isn't.

The thing I'd like to achieve with D is to have my Bash or Perl 
script call a command line D application that finds the current 
installer window x,y, hides the Cocoa-based window, draws my new 
Cocoa-based window to replace it at the same x,y,w,h as the other 
one, and then runs curl command to download the file, then uses 
the D application again to stop showing my custom window, unhide 
the installer window, and exit the Bash script.

So, some things I need to learn in D:

* How to enumerate the currently visible Cocoa windows and their 
titles or internal names, along with their window handle.

* How to get the x,y of an existing Cocoa window by its window 
handle.

* How to hide a Cocoa window by its window handle.

* How to draw my own Cocoa window at an x,y coordinate.

* How to destroy my Cocoa window by its window handle.

* How to unhide a previously hidden Cocoa window by its window 
handle.

If I could pull this off -- I'd make a really nice OSX installer 
because I could have a small pkg file that downloads and runs, 
and then its window gets hidden and shows a more-user friendly 
window (drawn in D and Cocoa) to let the consumer know it's 
downloading a larger file, and then show the conclusion when 
done. Currently nothing like that exists on OSX, but does exist 
on Windows via the Inno Setup and InstallShield platforms.