vb Code:
Option Explicit
Declare Function SendMessage32 Lib "USER32" Alias "SendMessageA" _
(ByVal hWnd As Long, ByVal wMsg As Long, ByVal wParam As Long, ByVal _
lParam As Long) As Long
Declare Function ExtractIcon32 Lib "SHELL32.DLL" Alias "ExtractIconA" _
(ByVal hInst As Long, ByVal lpszExeFileName As String, ByVal nIconIndex _
As Long) As Long
Declare Function GetActiveWindow32 Lib "USER32" Alias "GetActiveWindow" _
() As Integer
Sub ReplaceIcon()
Dim Icon As String
Const NewIcon$ = "Notepad.exe"
'~~> Getting the icon from windows calculator
'~~> similarly you can extract the icon from any exe
'~~> if the application is not present in windows path
'~~> then give complete path and file name
Icon = ExtractIcon32(0, "Calc.exe", 0)
'~~> you can use 1 for big icon
SendMessage32 GetActiveWindow32(), &H80, 1, Icon
'~~> and 0 for small icon
SendMessage32 GetActiveWindow32(), &H80, 0, Icon
End Sub