Improve MacDecorator to work with tabbing and resolve drawing bugs

[mmadia]

hrev43255 got the MacDecorator compiling again. Read the ​haiku-commits changeset thread for more information on what to improve.

Here is a brief and incomplete summary:

Currently when you stack windows, the only way to switch between them is reaching them from the deskbar. I don't find that too useful.

Stack and Tile is now a mandatory system feature.

Apps may start relying on it and use it (to replace tabs in terminal or web+ for example).

I don't know yet how it will work for these. There are multiple solutions :

• Have a popup menu with a list of the stacked windows
• Have tabs anyway (split the titlebar in 2 if there are 2 windows,...)
• Have previous/next buttons
• make the windows tabbed when you combine them in a group and just resize the tab down by the number of windows grouped. Even if that doesn't make sense for the OS you are copying, (MacOS or Amiga, etc.) it seems like the easiest, most intuitive, and least painful way to integrate them with S&T.

[rehaby]

Added a patch file which fixes the drawing of windows without title bars

[pulkomandy]

Hi,

This patch does not solve the issues mentionned in the ticket. To avoid confusion it would have been better to create a separate ticket and put the patch there.

Anyway, the changes still look fine, so thanks for working on this.

[pulkomandy]

Patch applied in hrev51433. Next time please use git format-patch to submit your patch so you get credited for it properly.