The first advanced layout manager for ExtGWT (GXT) posted the 1.0 release today. Features include:
  • aligns components in a dynamic rectangular grid of cells
  • fully compliant with GXT layout mechanism
  • column and row specifications
  • horizontal grow, fill
  • horizontal alignments: left, center, right, fill
  • vertical alignments: top, center, bottom
  • sizes can be specified as: Pixel, Points, Inches, Millimeter, Centimeter and Dialog Units
  • resize weights
  • bounded, constant, minimum and preferred sizes
  • column and row groups
  • cell constraints
  • form builder
Not supported in the 1.0 release are vertical sizes, vertical fill and vertical grow.

See it in action at:

http://code.google.com/p/gxt-jglayout/