ListBox Scroll Behavior Depends on Physical Dimensions (138602)

MORE INFORMATION

The scrolling behavior of a list box depends on the physical dimensions of the listbox. The following program demonstrates this behavior:

*-- Instantiate a form based on custom form class, TestForm.
frmMyForm = CREATEOBJECT("TestForm")
frmMyForm.show

READ EVENTS

*-- Define a custom class based on the FORM baseclass.
DEFINE CLASS TestForm AS FORM
     CAPTION     = "List Test"
     AUTOCENTER  = .T.
     HEIGHT      = 190
     WIDTH       = 300

*-- Add list box to the form.
     ADD OBJECT List1 AS LISTBOX ;
          WITH ;
          TOP            = 24, ;
          LEFT           = 24, ;
          HEIGHT         = 110, ;
          WIDTH          = 130, ;
          CAPTION        = "Next"

*-- Add command button to exit the program (form).
     ADD OBJECT cmdQuit AS COMMANDBUTTON ;
          WITH ;
          TOP            = 60, ;
          LEFT           = 180, ;
          HEIGHT         = 29, ;
          WIDTH          = 100, ;
          CAPTION        = "Quit"

*-- Add custom code to the Init event of the form.
     PROCEDURE Init
          THIS.LIST1.AddItem('One')
          THIS.LIST1.AddItem('Two')
          THIS.LIST1.AddItem('Three')
          THIS.LIST1.AddItem('Four')
          THIS.LIST1.AddItem('Five')
          THIS.LIST1.AddItem('Six')
     ENDPROC

*-- Add custom code to the Click event of cmdQuit.
     PROCEDURE cmdQuit.click
          THISFORM.Release
          CLEAR EVENTS
     ENDPROC

ENDDEFINE
*-- End custom class definition.
*-- End program.
				

Run this program. With the current Height property of the list box set to 110, there is not enough room in the list box to display the entire contents of the list box. Therefore, when you scroll down to the last item in the list box, the highlight bar stops on the last item.

To demonstrate the cyclical scrolling behavior, edit the program and change the Height property of the list box to 120. Then Rerun the program. Scroll down in the list box and notice that when you reach the last item in the list, the highlight bar cycles back up to the first item and starts scrolling down again.