Attached is a little FireFly Project with Bitmaps in Menues.
Uses original size and resized bitmaps.
Here is the function that does the job:
'--------------------------------------------------------------------------------
' MenuAddImage
' Assign a bitmap to a menuitem
' Example: MenuAddImage(HWND_FORM1_TOPMENU, IDC_FORM1_MNUOPENFILE, "IMAGE_RED13")
'--------------------------------------------------------------------------------
Function MenuAddImage(TopMenu As Dword, MenuItem As Dword, Bmp As Asciiz) As Long
Local hBmp As Dword
hBmp = LoadImage(app.hInstance, Bmp, %IMAGE_BITMAP, 13, 13, 0)
SetMenuItemBitmaps(TopMenu, MenuItem, 0, hBmp, hBmp)
End Function