I have read that gwt-ext is slow and it seems too bulky. How does this compare with Ext-GWT? Are there any other libraries out that can easily handle dragging, resizing, minimizing?
In my opinion there are no real worthy GWT widget libraries that I want to even consider. If there is a widget missing you can always try to get one included in the incubator, this way it will maybe end up in the GWT distribution one day.
The bigger, impressive looking ones tend to be a wrapper for an existing JS widget library. Which means that you have to pass on many of the benefits of GWT.
Others like Rocket GWT are a complete rewrite of existing widgets which ties you to another abstraction. That means that if you need extra widgets outside of the Rocket ones you will need to use widgets that follow different design principles.
I tend to stick to the default ones and I use the incubator widgets but I always try to keep those dependencies to a minimum since these are still changing dramatically (changing classnames, packagenames, complete design changes, ...). You do not want to keep on modifying existing code.
In most cases I just create my own widgets that does what I need and nothing more. That takes a lot less time to create than if I have to implement a complete API that would cater a lot more usecases.
Have you looked at http://www.smartclient.com/smartgwt/showcase/
The controls are licensed as LGPL, but advanced server site libs are only included in the professional edition.
we're having some success with Mosaic from the GWT incubator. You'll wish for better documentation, but once you get past that you'll find useful widgets (split panels, etc.) that you can mix with gwt's basic widgets.