> I'd like to have a GUI builder (preferably on Linux, or will run the 
> built GUI on Linux) that's as easy as Microsoft Visu ... 

Don't fight it ;-)

Drag+drop design for Rails (cross-platform):
http://www.sapphiresteel.com/Visual-Ruby-On-Rails-Drag-and-Drop
http://www.sapphiresteel.com/A-Brief-Guide-To-The-Visual-Rails
http://www.sapphiresteel.com/A-Brief-Guide-To-The-Visual-Rails,235
http://www.sapphiresteel.com/Visual-Rails-Workbench-screencast
http://www.sapphiresteel.com/Visual-Rails-Workbench-The-Import

Drag+Drop design for any .NET program running Ruby:
http://www.sapphiresteel.com/Ruby-and-NET-Making-a-Connection

Drag+Drop Design for Iron Ruby (.NET):
http://www.sapphiresteel.com/Ruby-In-Steel-For-IronRuby

best wishes
Huw Collingbourne

SapphireSteel Software
Ruby and Rails In Visual Studio
http://www.sapphiresteel.com
-- 
Posted via http://www.ruby-forum.com/.