Problems with setting application icon

Question

(I\'m using Visual Studio 2008, though I remember having similar problems with older versions as well.)

I\'ve tried several different methods (many of them mentioned

Answer 1

For anyone coming to this same difficulty if you are going to change ICON_BIG you must first send WM_SETICON with ICON_SMALL and then proceed to ICON_BIG.

For example:

SetLastError(0);
SendMessage(windowHandle, WM_SETICON, ICON_SMALL, (LPARAM)iconsmallHandle);
[do error handling]
SetLastError(0);
SendMessage(windowHandle, WM_SETICON, ICON_BIG, (LPARAM)iconbigHandle);
[do error handling]

You will need to use SetLastError after the first SendMessage to clear any returned error.

If you are just setting ICON_SMALL you can ignore ICON_BIG. For whatever reason in all of my tests you must set ICON_SMALL regardless if that icon needs to change or not, before attempting to change ICON_BIG, otherwise you will always get error code 0x6 (invalid handle).