>For listbox I would expect this code to be in Listbox.InteractiveChange.
Actually the code is very very long, the grid can be change from many controls, listbox, combobox (that I use for the header of grid), it's kinda difficult to explain whole project, but I'll try to make it simple,

myTable1
bodypart C(100)
color C(100)
combo N(10,0)

I make a temporary cursor on ;
grid.init()
Create cursor myTempCursor1 (qty N(10,2),part1 C(100))
WITH THIS
.RecordSource='myTempCursor1'
.RecordSourceType=1
.ColumnCount=2
.HeaderHeight=0
.Column1.Width=55
.Column2.Width=100
ENDWITH

And on listbox.interactivechange()
THIS.PARENT.myGrid1.AddData(This.Value)

myGrid1.AddData
Select * ........

Do vfpxtab WITH 'myTempCursor1'

THIS.COLUMNCOUNT=FCOUNT('myTempCursor1')
DIMENSION THIS.HeaderArray(FCOUNT('myTempCursor1')-1,1)
For i=1 TO Fcount('myTempCursor')
This.HeaderArray(i)=Field(i+1,'myTempCursor1')
THIS.COLUMNS(i).CONTROLSOURCE=FIELD(i,'myTempCursor1')
THIS.COLUMNS(i+1).Width=100
Endfor

This.Refresh()

Actually, if change to a same listbox.value twice, just like :
listbox.Interactivechange() &&& 1st Changes (eq, Value=5)
Grid.addData() &&&normal

listbox.Interactivechange() &&& 2nd Changes (eq, Value=2)
Grid.addData() &&&normal

listbox.Interactivechange() &&& 3rd Changes (eq, Value=5) same as 1st changes
Grid.addData()

on The last changes of Listbox.value, The last column of grid changed it's size to 75 even though I put 100 in a loop on grid.AddData(), but on the 1st changes, size of last column of grid is 100.