Tip 108: Flashing Controls to Get the User's Attention

Abstract
When developing an application in Microsoft(r) Visual Basic(r), you can =
use the
BackColor property to change the background color of a control. This =
article
explains how you can temporarily flash a control's BackColor property to =
draw the
user's attention to a specific control.

Changing a Control's BackColor Property
When designing a Microsoft(r) Visual Basic(r) application , you place =
controls
such as List Boxes and Text Boxes on a form. At run time, you can move =
the focus
to one of these objects by using Visual Basic's SetFocus method. Users =
can then
see that that particular control needs to be addressed in some way. For =
example,
if a Text Box receives the focus, users know they must type some text =
into that
control.

However, users may not actually notice that the focus has been set to a =
specific
control because the "rubberband" (highlighting) around the inside of the =
control
is not that obvious. To alert the user, you could change the background =
color of
the control from white to, say, red, to draw the user's attention to =
that control.
When the control loses the focus, you could reset the control's =
background color
to white. This procedure, however, means that the control would be a =
different
color as long as that control retained the focus. In some situations, =
this would
not be appropriate.

A far better solution would be to change the control's background color =
for just
a few seconds. The example program below "flashes" a control by quickly =
changing
the control's background color three times in succession. The Timer =
function is
used to cause a short time delay in the program. Each time a 2-second =
interval
elapses, the control's color is changed from white to red, then back to =
white.
The For-Next loop dictates how many times the control is flashed. In =
this case,
a value of 3 was used to flash the color three times. This creates a =
very visual
clue to draw the user's attention to that specific control.

Example Program
This program shows how to highlight the control that has the focus. Run =
the
example program by pressing F5 . Then click the Flash Command Button. =
Note that
the background color of the List Box control is changed to red and =
flashed three
times.

1. Create a new project in Visual Basic. Form1 is created by default.
2. Add the following code to the Form_Load event for Form1:

Private Sub Form_Load()
List1.AddItem "Item #1"
List1.AddItem "Item #2"
List1.AddItem "Item #3"
End Sub

3. Add a Command Button control to Form1. Command1 is created by =
default. Set
its Caption property to "Flash".
4. Add the following code to the Click event for Command1:

Private Sub Command1_Click()
FlashControl List1
End Sub

5. Add a List Box control to Form1. List1 is created by default.
6. Create a new function called FlashControl. Add the following code to =
this
function:

Sub FlashControl(C As Control)
Dim OldColor As Double
Dim Delay As Double
Dim X As Integer
=20
OldColor =3D C.BackColor
For X =3D 1 To 3
C.BackColor =3D QBColor(12)
Delay =3D Timer
While Timer - Delay < 0.2
DoEvents
Wend
C.BackColor =3D OldColor
Delay =3D Timer
While Timer - Delay < 0.2
DoEvents
Wend
Next X
C.SetFocus
End Sub