FIX: Combo Box Behaves Erratically with Timer Control

MORE INFORMATION

Steps to Reproduce Behavior

1. Place the following code in a program and run it:

      PUBLIC oform1
      oForm1=CREATEOBJECT("Form1")
      oForm1.Show
   
      DEFINE CLASS form1 AS form
         Height = 297
         Width = 579
         AutoCenter = .T.
         Caption = "ComboBox/Timer Example"
         Name = "Form1"
   
      ADD OBJECT timer1 AS timer WITH ;
         Top = 270, ;
         Left = 278, ;
         Height = 23, ;
         Width = 23, ;
         Interval = 1000, ;
         Name = "Timer1"
   
      ADD OBJECT combo1 AS combobox WITH ;
         RowSourceType = 1, ;
         RowSource = "Test 1,Test 2,Test 3,Test 4", ;
         Height = 24, ;
         Left = 239, ;
         Style = 2, ;
         Top = 180, ;
         Width = 100, ;
         Name = "Combo1"
   
      ADD OBJECT check1 AS checkbox WITH ;
         Top = 239, ;
         Left = 239, ;
         Height = 17, ;
         Width = 100, ;
         Caption = "Timer Enabled", ;
         Value = .T., ;
         Name = "Check1"
   
      ADD OBJECT edit1 AS editbox WITH ;
         FontBold = .T., ;
         FontSize = 8, ;
         BackStyle = 0, ;
         BorderStyle = 0, ;
         Height = 165, ;
         Left = 6, ;
         ReadOnly = .T., ;
         ScrollBars = 0, ;
         SpecialEffect = 1, ;
         TabStop = .F., ;
         Top = 5, ;
         Width = 564, ;
         Name = "Edit1"
   
       PROCEDURE check1.Refresh
         ThisForm.Timer1.Enabled=This.Value
       ENDPROC
   
       PROCEDURE check1.Click
          This.Refresh
       ENDPROC
   
      PROCEDURE edit1.Init
         This.Value="A Timer is running when Timer Enabled is checked." ;
         +CHR(13)+CHR(13)+ ;
         "Whenever a timer is running (Enabled=.T., Interval>0, lower values";
         +CHR(13)+ ;
         "make it more likely to show problem), both user defined and system";
         +CHR(13)+ ;
         "(VFP) dropdown list ComboBoxes (Style=2) don't work.";
         + CHR(13) +CHR(13)+ ;
         "When the Timer is on, select Test 1 or Test 4 and it usually";
         +CHR(13)+ ;
         "doesn't select."+CHR(13)+CHR(13)+ ;
         "With the Timer control on, select Test 3 twice in a row and the" ;
         +CHR(13)+ ;
         "checkbox is often unchecked automatically."+CHR(13)+CHR(13)+ ;
         "Turn off the Timer and the ComboBoxes work properly."+CHR(13)
      ENDPROC
   
      ****The following code fixes the problems*****
   
      *PROCEDURE Combo1.Valid
      *This.Refresh
      *ENDPROC
   
      *PROCEDURE  Check1.mousedown
       *  LPARAMETERS nButton, nShift, nXCoord, nYCoord
        * WAIT "" TIME .01
      *ENDPROC
   
      ENDDEFINE
   						

2. With the Timer enabled, the "Timer Enabled" check box is selected by default, make several selections from the combo box. Select the "Test 3" item and notice the check box becomes unchecked.
3. Clear the "Timer Enabled" check box and make selections from the combo box. The object acts normally.

   PROCEDURE Combo1.mousedown
   LPARAMETERS nButton, nShift, nXCoord, nYCoord
     thisform.timer1.enabled= .f.
   ENDPROC

   PROCEDURE Combo1.InteractiveChangeEvent
   LPARAMETERS nButton, nShift, nXCoord, nYCoord
     thisform.timer1.enabled= .t.
   ENDPROC