Runtime navigation to and from a tab canvas—and between the canvas' tab pages—is subject to a few rules and restrictions.
At runtime, tab canvases are displayed automatically in response to navigation in the same manner as content and stacked canvases.
SYSTEM.CURRENT_ITEM and SYSTEM.TRIGGER_ITEM can legitimately not have focus, and may even be invisible, when a tab canvas has focus. Clicking on a tab canvas gives it focus but does not change SYSTEM.CURRENT_ITEM.
There are a number of ways to switch between tab pages at runtime. The most direct method is to click the labelled tab at the edge of a tab page. End users also can use the right- and left-arrow keys to switch between tab pages, but only if the labelled tab has focus (i.e., focus is not in an item or the tab canvas). Switching tab pages in response to navigation is similar to displaying a hidden stacked canvas in response to navigation: if navigation occurs between an item on tab page TP1 and and item on tab page TP2, Oracle Forms automatically displays TP2. If navigation to an item on another tab page fails (due to validation), Oracle Forms