The following was taken, verbatim, from the JBuilder3.5 help... Weight Use the Weight constraints to specify how to distribute the extra container space vertically (weightx) and horizontally (weighty) when the container is resized. Weights determine what share of extra space each component gets when the container is enlarged beyond its default size. For example, if you have three components with weights of 0.0, 0.3, and 0.2 respectively, when the container is enlarged, none of the extra space will go to the first component, 3/5 of it will go the second component, and 2/5 of it will go to the third. Note: If all the components have weights of zero in a single direction, the components will clump together in the center of the container for that dimension and won't expand beyond their preferred size. GridBagLayout puts any extra space between its grid of cells and the edges of the container. Weight values are of type double and are specified numerically in the range 0.0 to 1.0 inclusive. Zero means the component should not receive any of the extra space, and 1.0 means component gets a full share of the space.
I don't see any reason why the weights cannot be greater than 1.0. Suppose a row has 3 buttons which have weightx values 3.0, 4.0 and 5.0 respectively, then GridBagLayout calculates the relative weights by proportion, i.e. 3.0/12.0, 4.0/12.0 & 5.0/12.0 resp.
Gravity is a harsh mistress. But this tiny ad is pretty easy to deal with: