This sub sends a message to a combo box, setting the width of the drop down area. It is only a wrapper for the SendMessage API function. Pass it the combo box, and the new width, and it will send the appropriate message.

Declarations

Paste this into the declarations section of a module:

Public Declare Function SendMessage Lib "user32" _
Alias "SendMessageA" (ByVal hwnd As Long, _
ByVal wMsg As Long, ByVal wParam As Long, _
lParam As Long) As Long

Public Const CB_SETDROPPEDWIDTH = &H160

Procedure

Public Sub SetComboWidth(oComboBox As ComboBox, _
lWidth As Long)

' lWidth is in pixels

SendMessage oComboBox.hwnd, CB_SETDROPPEDWIDTH, lWidth, 0

End Sub

Notes

Use this sub where you like: it does not have to be in the combo's dropdown event.  Also, this code will not work if you specify a width that is less than the width of the combo box control.  i.e. you can only make the drop down list part of the control wider that the control itself.