By default, the columns that display in a data-aware control are determined at run-time based on the Columns that appear in the DataSet. If the data structure at the data source has been updated and is incompatible with your application, a run-time error is generated when the situation is encountered.
JBuilder offers support for data persistence as an alternative handling of such sitations. Use this feature if your application depends on particular columns of data being available in order for your application to run properly. This assures that the column will be there and the data displayed in the specified order. If the source column of the persistent Column changes or is deleted, an Exception is generated instead of a run-time error when access to the column's data fails.
You can make a column persistent by setting any property at the Column level (for example, an edit mask). When a column has become persistent, square brackets ([ ]) are placed around the column name.
To set a Column level property,
In the Column Designer, the columns for that data set are displayed in a grid in the UI Designer. A toolbar for adding, deleting, navigating, and restructuring the data set is provided.
Restructure compiles the this component and launches a separate VM to perform a restructure of the DataStore associated with the data set. While the Restructure is running, a dialog box is displayed to show the status of the restructure and to allow you to cancel the restructure.
You could also do all of your column manipulation through the Column Designer. You can right-click on the header of the grid to select (or unselect) a column property. That property is added to, or removed from, the grid. This in convenient for setting global properties for every column in a data set, for example, width.
To close the Column Designer, double-click on any UI component in the Component tree, or single-click on a different component, and select Activate Designer. In other words, the only way to close one designer is to open a different one.