How to change the icon in taskbar using windows api

Question

I am writing a small windows application.

I want to create a installer using nsis script.

I know how to change the default application icon, start menu icon

Answer 1

It's important to change all icons, including the application, both small and big:

//Change both icons to the same icon handle.
SendMessage(hwnd, WM_SETICON, ICON_SMALL, hIcon);
SendMessage(hwnd, WM_SETICON, ICON_BIG, hIcon);

//This will ensure that the application icon gets changed too.
SendMessage(GetWindow(hwnd, GW_OWNER), WM_SETICON, ICON_SMALL, hIcon);
SendMessage(GetWindow(hwnd, GW_OWNER), WM_SETICON, ICON_BIG, hIcon);