Form rendering basics

Get the essentials about form rendering.

In the graphical mode (GUI mode), forms are not displayed in a fixed text-mode screen. Application windows can display complex layouts and are resizable by the end user, if the platform allows window resizing (mobile devices versus desktop platforms).

When developing with command line tools, forms are designed with .per form specification files, which are text files. In order to display text-based forms in graphical mode, the text-based form definitions must be converted to graphical forms, which implies specific layout rules. These rules are explained in this section.

We distinguish two type of form rendering techniques:

Grid-based rendering, based on a grid of cells, to place and size form elements.
Stack-based rendering, where all form elements are place over each other vertically.