The Tab keys provide a method to cycle through the input widgets of a user interface. Most input widgets have an attribute called TAB STOP that is set to 1 by default. When you cycle through a user interface with Tab or Shift-Tab, the pointer (which may change shape based on the widget that it jumps to) will stop at an input widget if its TAB STOP attribute is 1. If a widget's TAB STOP is 0, the pointer will not stop at the widget when you press the Tab keys.
Example: Using Tab Groups
For example, when you copy and run the Tab Groups program (see Copying Example Programs for procedures) the following display appears For this display,the TAB STOP attribute is set to 1 for PUSHBUTTONs on the left column and is set to 0 for PUSHBUTTONs in the middle and right columns.
When you use the keyboard to cycle through this user interface, as you press Tab or Shift-Tab you can only cycle through the PUSHBUTTONs on the left (R1_C1 through R4_C1).To get to a particular PUSHBUTTON in the middle or right columns, you must tab to the appropriate PUSHBUTTON in the left column in the same row and then use the Arrow keys to cycle through the row.
Each row in this display constitutes a tab group. Physical layout does not define the order of the tab group. Tab group order is defined by the sequence in which the input widgets are created. If you ASSIGN one widget with a TAB STOP of 1, any following widgets of the same type with a TAB STOP of 0 are part of that tab group, until you ASSIGN another widget with a TAB STOP of 1.
