Response to: to create rich GUI for monomac

Revision 1
One possible option is to use System.Windows.Forms on Mac OS. You can even develop the code on Windows. If you do everything accurately, without using any platform-specific or other incompatible feature, this code will work on Mono without recompilation even on Mac.

However, from what I ever saw, Mac OS X is the platform most hostile to foreigners. In particular, Mac UI has a different concept of a main menu, which is common for different application but gets different content as you switch the application. If you run Forms application having a menu under Mac OS X, you see both regular Windows-style application menu, and also the ugly Mac-style "Main Menu" on top, pretty much irrelevant to anything reasonable. Also, there is no such a strict coordination between activated applications and applications on top in Z-order, like you have on Windows. This should be taken into account.

I found some resolution of the main menu: you can use MonobjC on top of mono (and the command line will be "monobjc your_application.exe", not ""monobjc your_application.exe" and have two UI threads: one running System.Windows.Forms.Application, another one — Cocoa Application showing just the Mac-style main menu (and, optionally, something else). You still can build such application using MonobjC for Mono for Windows, but under Visual Studio, it won't allow you to debug code and use the Designer. This is possible using the MonoDevelop UI:
http://en.wikipedia.org/wiki/Monobjc[^],
http://en.wikipedia.org/wiki/Cocoa_(API)[^],
http://www.monobjc.net/[^],
https://developer.apple.com/technologies/mac/cocoa.html[^],
http://en.wikipedia.org/wiki/MonoDevelop[^],
http://monodevelop.com/[^].

Please see my past answers:
Mono Recommendations For Windows and Mac Deployment[^],
Programming for ipad/iphone on Windows 7[^],
about mobile operating systems[^],
Learning write c# for mac[^],
Need to make small apllication that runs on iphone-Ipad (maybe stupid question : ( )[^],
Learning write c# for mac[^],
how can i make mac software?..............[^].

—SA